there are a few things to consider. first is what are you going to do with it. ride trail, dunes, woods, hunt or do work with it. if you are going to hunt with it get an atv with at least 450cc and 4 wheel drive. go bigger in cc if you can. if you are going to work with it get 650cc or bigger and 4x4. for trail, dunes and woods, start with at least 450cc. if you do mostly dunes 700 and bigger is the best with dune tires. the larger cc machines will be real tight to the edge of the trail in the woods so the 450cc machines seem to have the right amount of power and size for the woods. any cc and size works well on the open trail just make sure the machine fits your body and style. automatic or manual shifting. the larger cc a machine is, the heavier it is.  plastic that is scratched, is easily replaced by oem plastic or aftermarket (lower cost). sometimes it is better to buy a machine that runs good and has a clean chasis but worn or faded plastic. the cost will be lower because it "looks bad". you save a few inital dollars.  install new plastics and you have really good looking machine that runs well. honda, yamaha, polaris, suzuki, kawasaki, and arctic cat all have good machines and dealers to get parts or service anywhere