I use 2mm thick black acrylic bases, which I get laser cut from a local online store. They are 50mm wide from flat edge to flat edge...so no good for hex map play (but you could just as easily get smaller ones cut), but I play mostly Alpha Strike and very occasionally use the Miniature Rules for CBT. I prefer the larger footprint as it makes them more stable and gives you the opportunity to do some nice base-work.
I use a course grit sand paper to scratch up both sides badly to help with adhesion of glues and basing materials...only takes a few seconds on each side.
To glue the mini's to the base, I use ZAP Gel, which is REALLY strong.
Below is a pair of the new plastic Wolverines I've started working on last night.