I've used bamboo but it wasn't long lasting enough for my money. (bought at the Dollar Store since it doesn't grow here). I tried maintaining the bamboo with a coat of linseed oil but it seemed any part stuck in the ground would need that yearly, so a huge amount of work, and after a couple of years they got white rot anyway..
I have some metal cages too that are a folding triangle, nice design for storage and serviceable although they aren't really big enough. Those that weren't painted/coated also started to rust in short order. I got some rust paint on them this spring and I used the same (sticky and noxious smelling!) paint on a few bamboo stakes to see if that would improve their longevity issue... time will tell.
The only product for tomato support that I'm still impressed with its longevity, is rope.
Nylon I think.