I have played through SR2 and SR3 multiple times and love them both for pretty much opposite reasons.
For SR2, I loved it for the fact of just how much freedom it exuded. The character creator was and still is amazing for me, and so too were the wardrobe options. I mean, how many other games can you get away with running around like some meth head, dressed up in nothing by tighty-whities, a sweater vest and neon green football helmet? SR2 essentially gave you the a big box of LEGOs and said go have at it. Further, the storyline felt more purposeful. You start in SR2 as some nameless thug waking up from a years-long coma in a jail. You spend the entire game afterward taking Stilwater by force, and essentially becoming a true kingpin of crime, and it feels more like a solid victory than it does in SR3.
SR3, on the other hand is concentrated fun, but at the loss of things that made SR2 so great. The character customization is still pretty nice, but not quite as absurd as you could be in the previous game (although the character models are much nicer looking this time around). And the story knows it is a ridiculous setup right from the get-go, so it doesn't try to drum up any drama because otherwise it would contrast with the overall insanity in the game. But the reason why I probably put SR3 just a little bit higher than SR2 is simply because the game is a hell of a lot more fun to play than SR2 (and much much more fun than SR1). The driving and shooting mechanics feel much better, and the melee combat is night and day different. They did slim down the activities, but considering how all feel a lot more fun than the previous iterations (sans one of the Trail Blazing activity in SR3 which I absolutely hate), I can let it go. It would be cool to see them be placed back in.