I like both, each has pros and cons:
ABS: softer to the touch, double shot legends that are crisp and last forever. Some ABS are crap, just thin plastic, but SP DSA is really nice, not to mention GMK, with that really close to perfection Cherry profile and thick ABS.
PBT: You can dye sub those, that means any cool legend you can design, any font you want. Never develop shine, and if the PBT is thick a really nice typing experience, even with that roughness that has it's charm