The most important feature to me is how usable the middle mouse button is. Beside MoI I mainly using Houdini, and it's amazing how important this button is for navigation ... so for my taste middle click need to be ultra soft and accurate (no scroll wheel by 'mistake' that would force you to use excessive pressure). In that area I'm really happy with the Rival110 (SteelSeries), I don't think that specific model is still selling tho, but I guess current models use the same clicking design ... hopefully !