I use a Deathadder 2013 and love the thing. Its fine for shooters, I also play DOTA2 with it and find the thumb buttons are fairly useful.
The Imperator looks to be more of a mobile mouse given the size and shape, so I wouldnt go with that.
The Sensei looks to be functionally the same as the Deathadder, its just going to be a question of aesthetics and ergonomics between them. It looks more optimized for a fingertip grip, while the Deathadder is more suitable if you have a palm or hybrid grip.
Explanation on the different grips.http://www.youtube.com/watch?v=luCxbVslSFM