After reading a whole slew of articles, essentially, the choice is yours to make.
There are articles in support and against both sides of the coin. Both hold onto bacteria and both are soft enough to not damage your precious knives. Wooden ones work well as trivets (for putting hot pots and pans on) but plastic ones can go into the dishwasher.
Function is really important to me when choosing a cutting board. It MUST be big enough.
There are articles that talk about wood vs. plastic and others that discuss sanitation of your cutting board and pros & cons of various materials like glass. If you are STILL undecided after that, you could read a study by University of California at Davis.
I usually end up deferring to my preference for natural materials, like wood. I also looked at this article on cutting boards and how to season them, as well as this article by TV hosts Anna & Kristina who put products through a rigorous testing. And often when I am unsure about all things food, I defer to Michael Smith.
Whatever it is you are looking for in a cutting board, I know you will find it!