Alright, just to be clear, I'm not asking people about their opinion about the franchise or evaluating any of its part so far.

Now I'm a big fan of the Transformers Movies, never been into comics, plus movie graphics are way cooler in my opinion. So after the third movie, I noticed a bit of repetition in how making a Transformers movie works, then I wondered what could the next movie be possibly about? (If there is a 4th one) So I decided to write a general outline for what I think is a good idea for a 4th Transformer movie, and thought I'd post it here to get feedback and evaluation from anyone who is interested to read on ahead.
(Warning: It is very, very long)

I will illustrate the outline in points:

_ 6 months after the last movie ended, the humans are busy rebuilding Chicago, Sam now works as the UN secretary's advisory on all things transformers because of his experience with them

_ A new "spark" arrives from outer space (it's source is unknown and not revealed), and lands at a junkyard, the spark attracts metallic parts from its surroundings and produces a new big transformer (possibly a bit smaller than Optimus). He goes around discovering the planet through hacking into computers, and learns language, technology and all what happened with the autobots since they arrived (he hacked into gov files). He eventually transforms into a jet fighter, but in a way that doesn't make him look ugly in robot form ( aircraft transformers so far look bad in robot form in my opinion ). I didn't know what to call him, so I just called him E-new

_ 3 months later, another spark arrives at another place and a new female transformer forms; she is noticed by the E-new, and he takes her in and they both train and develop weapons, deciding to stay away from human and autobots' discovery for now. She is called Rilna ( lack of creativity, I know ) and transforms into a helicopter (not sure which yet)

_ Since Megatron died, the decepticons have broken up, and they started fighting each other for the right to be leader, so total anarchy breaks out between them

_ 1 year after the end of the last movie, a group of decepticons attack earth, the autobots are dispatched, but E-new and Rilna are closer to the action zone and decide to step in and fight the decepticons; the battle starts and the decepticons start losing, then soon after autobots arrive and take out the remaining decepticons. The autobots meet the new transformers and they all go back to the autobot base.

_ The humans (represented by the usual evil minister) are mad about the attacks and for not being told about the 2 new transformers, and demand that from now on they stay in the base as part of the autobot group, but E-new steps in saying that he and Rilna are not autobots; he explains that they remember "starting life" on Earth, so they are citizens of this planet and not from cybertron, and that they have free will to not be on either side, they decide to call themselves the E-bots (short for Earth bots), and that they will fight the decepticons because Earth is their home and they want to defend it, but also their faction is not bound by any political agreements with any government

_ 2 weeks later, 2 other groups of decepticons attack the planet, but once they arrive they start fighting each other as well as the autobots, and here the autobots and humans find out about the anarchy in the lines of the decepticons

_ 5 month from that, (the autobots and humans are oblivious to the following ) a previously less powerful decepticon called Xtron (again, creativity) has formed a strong force and established dominance over the other decepticon groups. He is now in the place of megatron. One of the decepticons accidentally (no idea how though) finds an ancient map and brings it to Xtron. Xtron finds out from his scientist ( new decepticon too) that this map is encrypted in the ancient language by the primes and can only be deciphered from someone who knows the language, and that the last 2 transformers to know it are optimus and megatron; also he finds out that this map shows the location of an ancient guardian transformer buried amongst the stars; in the meantime, 3 new sparks arrive on Earth and 3 new transformers (2 males, 1 female) join the E-bots

_ Xtron begins a plan to bring back megatron so he can decipher the message

_ An organized attack from the decepticons on Earth to cause a distraction, while two decepticons sneak off and kidnap sam

_ The decepticons contact bumble bee, and warn him that if he goes to any of the other autobots for help Sam will be killed immediately. They inform him that he must acquire the matrix of leadership from Optimus and bring it to a specified location to exchange for Sam

_ Bumble bee goes back to base and ask Optimus about the matrix and its history, Optimus proceeds to tell him about it while taking out of his body; bumble bee surprises Optimus with a cheep shot, takes the matrix and escapes the base, the autobots follow him but Optimus says not to harm Bumble bee who eventually loses their tail

_ At the exchange location, Xtron goes back on his deal with Bumble bee, he takes the matrix by force then leaves, ordering the 3 remaining decepticons to finish him and Sam off, but as they start that, the E-bots arrive and defeat the three decepticons. Bumble bee and Sam explain what has happened, and E-new assures Bee that Optimus will understand, so they head back to autobots base

_ Optimus is furious with Bee, but after Sam explains, he forgives him but is still angry; the humans show concern for the loss of the matrix and the decepticons' intentions

_ Elsewhere in the basement of a museum where Megatron's body is kept, Xtron and other decepticons attack and bring Megatron back to life with the matrix. The decepticons escape to their ship; tension grows between the humans and the autobots

_ E-new, without consulting the autobots or the humans flies to the decepticon ship to gather information, leaving Rilna in charge of the E-bots telling her to defend Earth no matter what

_ E-new sneaking around the ship, discovers an undercover autobot (small in size) who shows him how to sneak up on the command deck of the ship; Xtron explains to Megatron that he is now leader and that Megatron owes his life to him and so he will make him second in command. Xtron goes on to explain about the guardian and his plan to bring him back to life with the matrix and use him to attack Earth and destroy it, Megatron is impressed and agrees to decipher the map. E-new overhears this, but his position is soon discovered, he fights off the attacking decepticons but eventually captured and imprisoned, with Xtron wanting to keep him alive to watch his planet Earth get demolished. The undercover autobot reaches E-new, and tells him that Megatron located the Ancient Guardian on Mars; E-new gives the the undercover autobot a booster rocket from his parts and tells him to go to Earth to warn the others.

_ On mars the decepticons arrive and resurect the guardian; meaniwhile the undercover autobot reaches Earth. He informs the autobots and E-bots of what has happened. Then Optimus explains to the humans ( who are as curious as always ) who the Guardian is. He says that he has heard the story and was not around at the time to witness it. The ancestral transformers where ruled by the Primes, and where allied with an alien race on another planet. But some rogue transformers were envious and wanted the leadership for themselves, so they built the Guardian, a huge and very powerful transformer that has no personality, but only follows orders. The guardian was instructed to destroy all life on the planet of the Primes' allies; there was a big battle which the primes lost and all life on the planet was destroyed, but it was all in sacrifice for creating the Matrix of Leadership, which they used to send the Guardian into hibernation. After this, the rogue transformers where destroyed, and the Guardian buried on the planet he destroyed, which now is revealed to be Mars. The early Primes then locked the location of the guardian in the encrypted map and made their best it is never found again ( btw it is to mention that these Primes where before the Fallen was created ).

_ The autobots, E-bots and humans start preparing to fight off the guardian. The decepticons and the Guardian arrive at a city ( city X bcz I don't know which to pick ), and level it completely before the autobots arrive. The guardian appears to be able to imitate technology he witnesses. Meanwhile, E-new escapes from his prison secretly, and captures the scientist decepticon, he asks him how to destroy the guardian; the scientist, deciding to change sides in the war, tells him that the matrix of leadership must be merged with the Guardian's own sword, and then this sword-matrix used to attack the Guardian, then he will be destroyed; the two then escape the ship towards Earth

_ The decepticons and the Guardian arrive in New York under instructions from Xtron to set a big example for all humans and make them feel the fear by attacking one of the largest cities in the world. Here is the final battle, Autobots, E-bots, and humans attack decepticons and guardian. All the usual final battle happen, little attack, slight victory, then things start going for the worse; then E-new and the scientist arrive and join the battle, telling Optimus of what needs to be done; E-bots arrange in formation and attack the guardian from all directions to acquire the sword. The guardian copies E-new's booster rockets and a flying chase begins; but through careful planning and execution, the E-bots use the small spaces between buildings to bring the guardian to the ground and E-new knocks the sword out of his hand and then acquires it while the other E-bots keep distracting the Guardian. Meanwhile, Optimus ferociously attacks Megatron and Xtron, and after a bit of fighting kills one of them ( I couldn't pick which, because one of them has to carry on in the next movie, I prefer Xtron stay alive though ) and aquires the matrix. The humans (tanks, jets, battleships ...etc ) and the rest of the autobots are fighting off the rest of the decepticons. The guardian overpowers the E-bots, and heads for his sword; E-new and Optimus meet up and merge the sword and the matrix, but the remaining decepticon boss ( in my preference Xtron ) attacks them and steals the new weapon, and goes for the kill on Optimus, but Rilna and Bumble bee arrive in the nick of time to stop him, but the Guardian is closing in. Optimus gets up and attacks Xtron, knocking him out, and getting back the sword-matrix. The guardian is on the way to attack Optimus, but E-new has gotten up and starts to fly around the guardian; Optimus sees him and throws the weapon as far as he can towards E-new who goes after it, the Gaurdian is furious and Optimus decides to attack him to distract him. After much bravery from Optimus in an overpowered battle, Optimus falls to the ground, and the Guardian closes in for the kill, but E-new, having retrieved the weapon, flies in and attacks the Guardian from the back, killing him with a single stab that destroys the guardian's very powerful spark.

_ Meanwhile, Xtron and the remaining decepticons escape the battlefield as the Autobots, E-bots and humans claim victory. The matrix of leadership separates from the sword and returns to Optimus.

The End :D

Hope to hear your comments regarding this outline. I know its long and as a movie it would be really long too, but transformer movies are usually long to explain the story. I just see this as an epic battle, and goes away a bit from the conspiracy theory pathway that the last two movies took. Thanks for your patience :D