I'm not shy about the fact that I have maybe some of the most bizarre gaming mice preferences you'll come across. Where a lot of FPS gamers will opt for a very slimline, lightweight mouse that's obsessed with gliding across their desk like it were ice skating, I'm not a fan. Instead of the claw grip most people are using, I've always preferred a palm grip, so I ever so slightly detest mice that don't have a dedicated groove for my pinky and ring finger.
To make matters more complicated, I've also been obsessed with an MMO mouse for the last year and a half now. With 12 programmable keys on its thumb side, I have ultimate utility for mapping in-game actions to the buttons I feel are appropriate, and I'm not sure I could go without them now.