I think TS4 is better. TS2 was amazing in its time and is still great, but most people prefer TS4 these days for a reason. However, you might as well try TS2 again if you're curious.
To me TS2 is a much slower, simpler, and slightly more difficult game. By slow, I mean that the pace of the game is different because TS2 animators put more detail into the animations. Sims open cabinets when cooking and use cars when traveling. There also aren't as many Sims and they don't age together. So if you're a fast-paced, non-rotational player all of that might be annoying, especially given that there are fewer skills and objects in TS2. But TS2 allows for lots of drama.