Plastic stocks flex and bend very easily. Bedding compounds have a difficult time adhering to them as plastic stocks expand and contract with changes in temperature. If you mount a bipod to the forend, with some pressure it usually makes the stock contact the barrel causing a point of impact shift. Plastic stocks are prone to vibrate and flex under recoil causing these forces to differ with each shot. They are cheaper to manufacture so do come on many lower price point rifles. So from and repeatable accuracy standpoint they are a very poor choice. Typically the injection molded plastic stocks are more designed for ease of mold release than how they fit the human anatomy.
Wood and laminate stocks are a better choice on your journey to improved accuracy. A proper bedding job can be done to most rifles sporting these stocks. They are much more ridged and do not flex like the plastic/composite stocks do. The downside to wooden stocks is that being a natural material they can warp or twist with changes in humidity. Laminated stock are far less prone to warp than standard wood stocks. Both retain the classic good looks and are warmer to the touch than any synthetic, but do require much more care and maintenance. Many bore cleaning compounds will lift the finish off of a wooden stock faster than you can blink, so care must be taken when cleaning a rifle.
Our #1 choice for an accurate stock is a molded fiberglass stock. These have the strength and rigidity required to unify the entire rifle. Many different shapes and features can be built into these stocks including length of pull and cheek weld adjustability. The finish color can be molded right into the gel coat on some of these stocks for an extremely durable, long lasting appearance. Different weights and compositions can be chosen dependent for the fill materials the manufacturer employes. This can help lighten up that ultimate sheep hunting rifle or increase the weight to help tame the recoil of the powerful .338 round at the range.
For truly ultralight stocks carbon fiber is employed as the structural shell of the stock, this material is generally stronger than steel but extremely light weight and rigid making it an ideal stock making material.
The stock you choose is an important step towards a great fitting rifle and achieving the accuracy you demand.
If a stock does not fit the shooter correctly, the chances of attaining repeatable accuracy is greatly dimished and the shooter may have to endure more recoil than is necessary from the rifle.