Need a new mouse

My logictech g600 witch i love Has started to lag when moving have tired on other places an pc's doesn't change anything so i'm looking for a new mouse An i don't really know what to look for under 120 dollar's. i was thinking of a steelseries sensei, steelseries ikari or logictech g400 the new version. but don't know what to go for when it comes to fps and first person games. i got a bit bigger hands then normal

Whatever fits your hand. G400 should be the closest one in shape to G600. But if you want a smaller mouse, I'd recommend Zowie AM or FK instead of Steelseries because they have better sensors. 

Is there any difference between zowie Am an FK? i have checked around but i am confused about the difference's

There's a good description of differences on the official site.