The answer is... it depends...
The science is out. Logically wood should be bad because it's not a smooth surface to clean but wood also has other interesting properties in that it can effectively draw moisture away from bacteria over time.
Plastic, when new is great, easy to clean surface, awesome. Problem is it quickly becomes scored and difficult to clean. We think if something is submerged in water, the water has actually reached the bottom of any grooves but this is not necessarily the case and removing any debris from the bottom of those grooves will be really difficult.
But... I wouldn't rely on the innate antibacterial nature of wood to be able to cut chicken on it, clean it, then use it to prepare salad. Some ingredients are just too high in pathogens. I never use a chopping board to cut chicken at all. if I want to cut it in some way, I do so in the packaging it was supplied in, then throw it away. Apart from that, my home (wooden) chopping boards are reserved for vegetables only and the vegetables are always clean enough that there is no visible soil before contact with the chopping board (E coli risk).
At work always plastic and replaced very often.
Edited by GMO, 20 November 2019 - 02:39 PM.