The Sims 3

I think for a lot of people The Sims 3 remains the peak of the series. The big addition here was that the whole neighborhood was one "load screen". E.g. you could have Sims walk between different houses and outdoor locations without having to call a taxi and hit a load screen. This was a game changer. It made it feel a lot more lively and interesting. It was especially good for meeting new Sims as you could just walk over to a location and chat up strangers.

The tradeoff is I recall the game being very hard to run. Even on newer computers it would chug. The other downside of this is it seemed like they didn't really do a great job of populating the world with new characters. You'd start off the neighborhood with the predefined families and then they'd kind of just wither away into a dead neighborhood. You'd have the "randos" in the public zones respawn but overall it kind of died after a while.

But all that aside it was basically all the good of Sims 2 but newer and shinier. I think they added support for like, I dunno, rounded edges and stuff for builders. I guess the other big stuff was the addition of personality traits and moodlets. Traits are things like "Crazy", "Cheerful", "Narcoleptic" or whatever that determine the types of aspirations, a carryover from 2, that Sims have. It's fun to try and roleplay but the aspirations eventually turn into a predictable series of boxes to check. Moodlets are basically temporary mood buffs and debuffs to Sims that occur if certain conditions are met. Again, they're interesting for a bit but then turn into another predictable condition you can just kind of take advantage of.

In the end, for me the Sims 2 remains the zenith. If they had fixed some of the stated core issues this would be a perfect game. As it stands it's a flawed masterpiece.