I have ordered from most all of the sources listed, with the exception of Big Daddy. Each seller seems to fill a purpose for me and I am thankful we are lucky enough to have so many choices. I try to spread my dollars around, as I want to support all of these folks. Sometimes though it just comes down to having to use the company that has the obscure part I am looking for more than using a personal preference.
Regarding rubber: I hope to someday be good enough to discern between the 200 different manufactures of rubber. In the meantime, I just use a company that has colors, last a while, but all use the same rebound/feel, and aren't priced like they are made with unicorn tears.