The shift keys from hashbaz's RGBY Group buy are the best ABS keys I've felt by far. Unfortunately, they will wear out pretty fast, as ABS doesn't have that great wear resistance.
I much prefer PBT, and use only PBT on the three keyboards I use all the time (Unicomp, CMstorm with SP PBT and Cherry G84-4101SPAUS). Yes, I'm considering getting a PBT spacebar to replace the ABS one on the CMstorm.
The looks of dyesub PBT are great (better than doubleshots if the colourscheme allows it) and the feel is vastly superior. I haven't tried POM yet, but I have read that it is "Slippery" feeling.