ORIGINAL: mouthcaller
To my ears the surface that sounds the best is glass.Glass won't work inthe rain with any striker that I've found. Glass sounds good with a variety of strikers but my favorites are laminate wood one-piece and carbon/graphite.
Now here is a man with excellent taste. I too, prefer glass (or at least my glass call) to all others. And I like to run it with a birch laminate striker. All three last season.... that call had a hand in.
Ceramic, from what little I've messed with it, seems more like glass to me than slate.
As I wrote before, and as you've read here from others, I think metal surfaces are the most unforgiving, but they do carry a long long way. Crystal has similar sound qualities with regards to volume and carry, but is easier to work with from a calling standpoint. They do have minor differences in sound though.