Zowie FK1 for fingertip and claw-grip users, this is pretty much a given. Alternatively, Mionix Avior 7000 if one prefers a more contoured thumb area.

For palm grippers, currently the Mionix Naos 7000 is my top recommendation. The G502 is good, but there's been an increasing reports of lens problem on them. I haven't encountered one though, so do take note and beware.

G502, I would consider this medium size, best if you can try this out at the store yourself though.
Large would be the MMO size mouse, probably not suitable for FPS as the side buttons is way too "much"?
Otherwise Mionix Naos 7000, which I think the comfort tops all current mouse.