My vote is for wood. Better traction, doesn't get hot, lighter, and lasts long enough.....
Also, if you start hauling other random stuff on your trailer (which i can guarantee you will), things will slide less on wood and be easier to tie down. Plus you can screw into wood. THis is awesome when trying ot secure things. Like when transporting cabinets, you just sink a few screws through the backs, and put on a strap or too over the top. Or if you want ot screw a tire "stop" block to the trailer it is easy.
Basically, its easier to modify and add things to the surface that arent' really permanent.
Just a few more ideas to consider....