I have an M90 and love it, it is shocking how quickly you learn to use all the different buttons and it's extremely comfortable to use --- Matthew 7:21 http://img15.imageshack.us/img15/2492/gyenyame.jpg
Take a look at the Corsair M95. I recently bought that and have been pretty happy with it. It takes a little getting used to, but I figure most mouses with a lot of buttons do. Plus it's my first real gaming mouse with more than the standard amount of buttons.
Edit: Clearly Knighted Dragon and I know what's up. :) --- Your body may be gone, I'm gonna carry you in in my head and in my heart, in my soul.
I can third the M90. I mostly use the extra buttons in GW2, the bottom one for dodge, the thumb one for healing, and the top ones for attacks above #5 (I hate moving my hand that far :P) --- "Are you going to buy this time? Or are you still just curious?" "Well, I supposed you could say I'm Buy-Curious" ~PSN - greeniebeanie