Afterward, the board should be wiped with vinegar to remove the bleach. So, you see, from a microbiological point of view, it doesn't matter much whether you choose wood or plastic, as long as you clean it properly. As I mentioned before, plastic is harder than wood, meaning it will dull a knife faster. Glass cutting boards are harder still. On the other hand, you can throw plastic and glass cutting boards in the dishwasher without having to worry about whether they'll warp and crack.
Wood is easier on knives but requires regular care in order to last.
Although pretty rare, my personal favorite is natural rubber. Its softness accepts the cut of a knife easily and seals itself afterwards. It's smooth and hefty and doesn't warp or retain odors. I tried a quick web search but failed to find what I'm talking about, so you're just going to have to imagine what cutting board bliss is like. You can see now why it's hard to give a straightforward answer.