There are many different kinds of resin.
I had a couple of Finecast models, but I think GW should not have employed the man from Cadbury's responsible for the Wisps bar.
I was impressed with the resin used by Anvil:
Almost no flash, no mould lines and parts go together as good as injection moulded plastic.
The PVC used in The Walking Dead figures is generally fine, but I have had a few drunken figures.