I believe LA doesn't go beyond Showtime so I would try that world. I liked it but I think AC is a better version and it doesn't matter if you don't have all the EPs. I believe someone has an updated cc free version of it as well that has another bridge replacing the Monte Vista bridge in the world. I saw it in the thread for the world.
I have the weirdiest bug with bridges in Angel City - they're all invisible except for the MV one. Are they all from Supernatural (the only EP I don't have)? I've tried installing/uninstalling the world a couple of times, even installed the cc-free version - same thing. They're invisible but seem to be functional - except for the one linking the city with the port, it just doesn't exist (there are motorboats at each bank of the river, but they're not moving, sims only get stuck in them).
Also the festival lot doesn't work for me - there are no festivals held there, but it's not a deal-breaker.
It's a shame about the bridges, otherwise AC would be my favorite custom world ever. I love the scenery and the layout, I have no lags (although quite a lot of unroutable sims), and it seems so full of life - I've never seen so many townies out and about before.
So I downloaded kiwi tea's Riverblossom Hills. (Note, I didn't use the link here, went for the one on the Official forums that has been updated for Generations.) Haven't really played much of it so I can't comment on the stability/performance side of things, mostly just been exploring it in Edit Town, adding/changing a few lots.
The world itself is really lovely. There's three sort of areas in it. There's the town itself (which in turn has a few areas, including the downtown area, the suburban streets, a swampy area, the military area and an industrial area. All really fit in well. No clashing or anything.), then lots of farm lands and empty spaces in the middle surrounding an old abandoned quarry, then a smaller area on the coast which is more of a modern, gentrified beach area. All of the characters from the neighbourhood in The Sims 2 are back, plus many new ones.
My only major criticism is that the lot sizes are incredibly small, namely in the town area. I'd say the average is about 20 x 20 and due to the roads being more curved it's difficult to place more lots on it. Buildings aren't my style but that's not a critisism, just my own taste.
Overall a great job. Will add a lot more playtime to the game for me. I recommend it but chances are everybody here already has it.