Some other keycaps (especially Unicomp and Matias) feel like a cat's tongue when new, before they're worn in. I'm still not overly keen on whatever plastic Matias use – it feels a bit rough and weird.
I do find that my FILCO keyboards (2 years old) have something of a greasy feel, but that may just be an accumulation of skin oil that's nothing to do with the plastic. I couldn't tell without a deep clean. It feels a bit like typing on butter.
Topre keycaps have a decent feel, but they visibly grease up in a way that I've not seen on any other board.
