For street use, I'd say aluminum, any aluminum, or a cheap steel... For wheeling, steel with reinforcements or forged aluminum.
All the el-cheapo rims suck. They're just too light. The reason people have to beat the lip back into place is because it was weak and bent in the first place. This is easily rectified by getting some .500x.500 keystock or 1/2" round rolled into a circle that is the inside diameter of the rim lip, then you just weld the damn thing in there. Or, do a weld on beadlock on the outside lip instead.
It doesn't matter what you buy, it will get scratched.