ABS will wear faster than PBT, but double-shot legends will last forever, whereas dye-sub legends will tend to bleed and fade a bit over time (a very long time, granted). I don't mind the "shine" that ABS keycaps acquire and I prefer double-shot legends, so most of my custom keycap sets are ABS. However, the PBT sets that I do have are terrific and have a different feel, sort of like soft pumice, which is pleasurable in its own way too. Really, you can't go wrong either way; the key is to get high-quality keycaps from a reputable manufacturer (like GMK or SP) regardless of style or plastic involved.