Use a Razer Mamba, exceptional piece of kit, brilliant software when used properly and very comfortable to use. Tactility of the buttons is superb, and when compared to the R.A.T series I find this to be better, not only due to there being no cable drag, but also because the buttons have a dip in them for the fingers to sit easily and not slide around on the surface. Very highly recommended for gaming.
Have a Magic Mouse, which is great for more or less everything out there but gaming due to the lack of an easily activated right click. Ergonomically it isn't bad, but when gaming I find the Mamba to be a better choice. Use this mouse for more or less everything but gaming, as it is such a pleasure to use in OS X.
Had Razer Ouroboros: overpriced piece of crap and broke virtually instantly, ergonomically it is awful when compared to similarly priced competition. IMO stay away.