Basically micarta and G10 are the same stuff - micarta uses a cloth fabric or paper base, and G10 uses a fiberglass cloth base. All use a similar resin, and are made by different manufacturers - in fact, you can pretty much make your own.
Formica (as in the stuff on your kitchen counter) is another reformulation - the Formica name comes from "FORmerly MICArta" - or so I've heard.
Very tough stuff, whatever variant you go with.