I've never built a stand, but I've read a fair bit about them. There is a member on RC - Uncleof6 - who is a tank builder and swears by 3/4" plywood stands for anything up to ~250G.
If you look at the commercially built stands out there, you'll see that virtually all of them are either plywood or 3/4" boards. If my wood working skills were up to it, I'd go wit plywood. Unfortunately, I can't cut a straight line :(