I do industrial epoxy floors for a living. Try to stay away from the water based stuff. Regardless of brand, the key to them all is proper surface prep. Muratic acid works well but prepping with a diamond grinder will 'open' the concrete for deeper penetration and remove old paint and oil spots.
if ne1 in the chicagoland area is interested in a 100% solids epoxy floor email me at j.michelau@comcast.net