My favourite personality trait is the frugal trait (I like that they can get coupons from the newspaper or online)

I don't like evil people, but I love to play Sims with the Evil Trait. I really like the manic cackling.

My favourite ones are:
+Genius: Hands-down the most useful trait EVER!
+Loser: A goldmine of dark humour (for Sims standards).

besides insane (because I love watching one of my men talking to himself like I said in another thread), I also love virtuous since I'm a music lover and it's so funny to hear them sing in the shower.

Eco-Friendly, cause they get good moodlets for the smallest things (gardening, taking a shower, etc). And workaholic so you can work from home.

I was creating families to populate a world with, and I noticed that hot-headed, grumpy, and mean-spirited were my most used traits. It was to the point where everyone in one family had one or two of those. I just love fatal flaws.

Other than that: savvy sculptor, insane, eco-friendly (thought it was useless until a bunch of my sims randomly rolled that trait), neurotic, over-emotional.

I have yet to use the frugal trait. I just love insane sims though, and neurotic is surprisingly useful. I'm also loving the Diva and Evil traits. I end up using Genius alot b/c my sims usually want their kids to be geniuses.

My favourite traits are Friendly, Good, Family-Oriented, Absent-Minded and Clumsy. I don't know why. I am none of these except the last three. :P

I love hot headed, insane, diva, snob and dramatic but I'm hesitating between neurotic and coward for my favorite trait. I like neurotic sims, how they keep on worrying about everything and their urge to check every appliance in the house is funny. Plus they can be very handy with their cleaning obsession. But lately I had an active sim with the coward trait and he cracked me up, he was always scared of something lol! When a coward sim is idle he often startles and has a very funny "Eek!" reaction. He would look anxiously all around him. Once he even went to anxiously look out from the window. The best one was when I "forgot" him outside, in the dark. Oy! He had the 'It's dark' moodlet and was panicking and checking all around him, apparently afraid of seeing a CLOWN!... And he fainted! So I'll vote for the coward trait, it makes unexpected fun moments :D

I always have Neat, Natural Cook and Handy on some combination of sims in the household.

Flirty.

I used to not care about traits and just gave them whatever was beneficial (Ambitious, artistic, bookworm, genius, etc...) but now I've been experimenting with other traits and I've come to like them, too. Hot-headed, coward, grumpy, commitment issues and others like those are just awesome.

I find myself always giving my Sims the Brave, Genius and Handy traits. I sometimes give them the eccentric, friendly, good, athletic, artistic, virtuoso or adventurous traits depending on what kind of Sim I want to make, but always Brave, Genius and Handy because they are so useful.