I was going to go for Prince of Persia - I even liked the second game, button mashing is a choice - but I give my vote to Resistance. Resistance had a great atmosphere, plenty of little lore collectibles like journal entries, characters were pretty good, the vehicle sections weren't some on-rails turret bullshit, they were just whole maps you got to drive a turreted jeep around with Cartwright, the weapons were creative and the weapon select wheel allowed you to make the most of them, and it had non-regenerating regenerating health, meaning you had bars of health and could only regenerate within one bar, consistent with the regenerative abilities of the Chimera, and offline co-op. I still remember going throiugh a particular level trying to blow up all the cars with my friend for the achievement.
Resistance 2 was also pretty good, weapons were nice, new enemy types, but more on-rails sort of things (like the Swarm fight), 2 weapon switch, regenerating health. The real advantage of 2 was the class-based seperate co-op campaign, which worked amazingly well with each of the three classes needing something from the others. The Soldier would run out of ammo, the Spec Ops couldn't heal, and the Medic had low damage output, but when they worked together, all I needed was one of each and we breezed through the hardest mode. The last kill system could have done with some work though, got down to a sliver of health and everyone starts busting out the air fuel grenades. -_- Unlockables for each class were creative too and lent themselves to a variety of builds. The co-op campaign even had background for what was going on in the world during the campaign at loading screens, and it was really well done.
Resistance 3 was a bit eh. The campaign was nice, but I don't know if it was just that they went for a survival sort of feel rather than a big military effort like the last two, it didn't feel the same. They brought back the weapon wheel, but I just didn't enjoy the atmosphere as much. Although it did deliver about the single most insightful moment of characterisation I've ever seen, where the brown haired Caucasian tough guy protagonist is pinned down, about to lose his only hope of success to a gang of idiots who don't even care, and he throws a little fit. Which is exactly the right reaction. Although in general, otuside of Capelli and Malikov, I didn't think characters were as good as in previous games. The co-op wasn't anything special and the multiplayer managed, unfortunately, to make you feel like you needed the upgrades longer-playing people had gotten to be competitive, which is a major turn-off for me, although I did enjoy the Hellfire and all the little abilities you could use.
tl;dr: Excellent atmosphere, fleshed out world, creative weapons, smooth class-based co-op in 2, 3 was sort of eh, but doesn't ruin the series for me.
) even if it had some boring parts.
