Even at the same thickness, PBT weighs more because it is denser. More mass = lower pitch.
The feel is affected by a few factors. The surface, the weight and the profile. PBT is "drier" feeling, almost like unglazed ceramic. It is also denser, which increases the impulse required to move the key.
The combination results in a less "cheap" sound and feeling, IMHO.
Personally, I prefer POM. It is even denser than PBT and I like the smooth surface feel.