I have definite biases. I build rifles, so my opinion is based on what I have seen that works. There is no substitute for wood for appearance, feel, and versatility. Wood is tough, durable, and strong. I have built wood-stocked rifles that have gone to SE Alaska, Africa, and Asia without a problem. If weight is not an issue, I generally recommend wood, it is pretty tough to beat for an all-around rifle.
That said, I also have several rifles with fiberglass composite stocks (not plastic or "synthetic", which generally means injection-molded foam or ABS) and I love them for their light weight and ruggedness. If weight is a consideration, I recommend a foam-filled stock, it will generally reduce weight by 1 pound or so. I am building a sheep/elk rifle for a client right now, and it will wear a fiberglass stock.