i agree with the previous poster...what feels good in the hand. I also like that they mentioned replaceable. will schusterick is using hard to find 10x kc pro aviars but can get ahold of them easier than i can so i use a dx big bead aviar, still a harder to find than going to dicks and picking up a new p&a aviar but not $50+ on ebay.
one thing also. the reason i use the dx and alot of pros use dx, pro d or kc pro is because of how well the plastic grabs the chains. firmer discs like ions, anodes and firm vibrams can cause spit outs in my opinion. my best friend was putting with ions and recently switched to a very soft putter and dropped up to 5 strokes depending on the course and now its getting harder to beat him unfortunately...dang it for my stupid advice.