There is little difference in strength of any kayak material. Kayak strength is mostly a function thickness and therefore weight. Composites (Carbon kevlar) have the same strength at lighter weight or more strength at the same weight. Composites have lower puncture resistance. Composite/kevlar may be a little stronger in heavy surf conditions, but it mostly depends on the layup thickness of the kayak versus the skin thickness used with the wood or fiberglass or thickness of the plastic. It is all a tradeoff on what you like. There is nothing inherently bad about wood or inherently good about glass. If you want a stronger, but heavier wood kayak just add some more fiberglasss and resin.
Design and construction style can also influence durability versus weight. See the internet site on Ray Jardin who constructed his own double out of kevlar and carbon. vacuum bagged with an airpplane like construction and came in at 39 pounds on a 21 foot boat.
Plastic kayaks tend to deform with heat and you will often see plastic kayaks that have dimples in the bottom where they have been deformed on a hot day while straped to the top of a car. It doesn't really hurt anything. Plastic kayaks are harder to repair but seldom need it. Personally I don't like plastic because the materail feels "dead"
Most rock garden types (Tsunami Rangers) use fiberglass because they are strong and are so easy to repair.
After all the original kayaks (Intuit kayaks) are made of skin and bones. In fact several friends of mine like to make skin on frame kayaks which are much easier to build than wood kayaks. These need to be babied a bit because they are more fragile and can be holed on oysters and sticks. But the tradition and pride makes up for it. In the end your choice of boat is like your choice of woman - a very personal thing. Some are a little more sturdy than others, some are more expensive than others and some require more maintenace. It is all a matter of choice and thank God not everyone likes the same one.