I like GTAIV's realism, but I prefer JC2's action. This game impressed me way more than any GTA for so many things like the enormous and varied setting, the great mobility, the impressive explosions...
I like action in action games, honestly. And I think that being able to jump on top of a moving car and then grapling to a military helicopter and hijack it just to make it crash into an unsuspecting enemy colonel qualifies as action.
Kudos for the creators. Already can't wait to hear about JC3.