Find a boat that you like, and think you will continue to like as you become a better kayaker, and purchase that boat. Don't buy a boat just because someone tells you it is an 'expert' boat. Find out what you like in a boat and use your own judgement in your purchase. Do not confuse how many years a person has been paddling with advanced skills. A person's skills will only increase if they work at increasing them.
Plastic is heavier, more resistant to damage, harder to repair.
Fiberglass is lighter, easier to repair, results in finer lines, but is more expensive. Fiberglass is generally more rigid than plastic, which can result in a faster boat. Fabric is labor intensive to build though a little less so than wood, fragile, and needs maintenance. They are generally more expensive to buy than any other kind of boat, but there are other considerations that may make them a better overall value. See section 5, folding kayaks, for more information.