i use 3/4 BCX its very nice and strong looks nice if you finish the outside too, but you have to wait a while for it to dry and for the smell to discipate if you finish it.... i have 3 big hugs tanks for snakes and lizards i made from them.
http://img376.imageshack.us/img376/4848/img2655jw4.jpg
this is a pic of the 3 first ones i built. i didnt finish them, just had to make big tanks fast to put stuff in. cheap too!