If you say plastic, can you tell me what it's made from? Did you know some of the resins from trees is made into plastics and alot of other products we use daily, not just toilet paper? Or tell me how clean a plastic factory is compared to a sawmill? Or do you think plastic products just grow naturally?
Plastics can be recycled in a matter of days, and even though wood will be used by nature to produce, in time, more trees..it just takes to long. So as long as you recycle....plastic all the way.
Wood by far, but unfortunately many things cannot be made out of wood. Many medical advances would have been impossible without the use of plastics. So use wood for as much as can be feasibly made out of it.
Plastics are made principally from petroleum products. There are some botique plastics that are produced for the hemp-wearing set using non-petroleum based hydrocarbons, but the resins don't stand up to stress over time. Wood is renewable. 'nuff said.
Like someone said above, if recycled, plastics can be better in the long run. IF, they are recycled. Plastics can be recycled over and over again into many many different things. Like carpet, containers, non-food bottles, fleece jackets, plastic lumber, etc. This takes a lot less energy to do than creating new plastic from virgin stock. But, especially if fast growing woods like Bamboo are used, and logging practices become more responsible and Old Growth forests are not razed to the ground to feed our expanding demand for wood/paper products...then yah. Wood is the way to go. The catch-all is responsibility by the manufacturers and the consumers. Use our forests more responsibly, recycle our plastic goods/use less of them. Create less, recycle/reuse more. How is that for dodging the question of which is more environmentally friendly? ;)
Production of plastic does considerable damage to the atmosphere, plastic also does not break down, so if you throw any away (including plastic bags) it'll be sat in dumps for decades, or if you try to burn it then black smoke will come off it *** it burns, that smoke is both bad for you and for the atmosphere. Things made of wood on the other hand, can cause pollution depending on how it's manufacture, but wood is biodegadeable unlike plastic, and nowadays when a tree is cut down more are planted, so there's no major issue there either.