Both SR2 and SR3 were fun, but for me, SR2 was definitely the better game. Tying the rewards like infinite ammo and super guns to stuff you did in the world rather than just waiting and buying them flat out made me feel much more involved.
Plus, after the initial "whoa" factor wore off, SR3 felt really dull to me. SR2 at least kept the gangs in seperate-ish storylines so you could choose how you played, (and felt like it had more content) while SR3 streamlined everything. It made it flow better, I guess, but Volition definitely pushed too far to the streamlined side.
Storywise, I dunno. Yeah, SR3 was over the top-crazy-fun, fine, but some of the decisions are pretty fucking stupid. Johnny getting shot to make the player "mad" at Phillipe (who was a terrible antagonist) the whole STAG thing, the pre-order bullshit and pretty terrible season pass DLC that didn't even integrate some/most of its items into the main game after you beat it...
Also, the city is pretty much dead. Barely any cars around, especially with the bugs that made no new cars/pedestrians spawn. To be fair, SR2 didn't do this well either, but Stillwater was a much better organized city that funneled you as the player to cool things. Steelport got boring much more quickly.
I dunno, rose-colored glasses or not, SR2 was the game where I had way more fun running around blowing shit up and doing stuff in the world, stupid poop spreading mini-games aside.