The Standard is, unsurprisingly, the standard choice. It's the middle in terms of pickup quality, binding and so on. You pay extra for other models for extra binding, greater build quality, better pickups, maybe more choice of finish.

The Studio is the lower end of the range, cheaper for being generally worse in the areas above. The only Studio I'd go for is the Robot, the self tuning one. It's $4k new, a few hundred dollars more than a standard Standard.

You should read reviews of the guitars around your price range, and the pickups. I've got BurstBucker Pro p'ups in my SG, and they're great - but you might like 490R & 490T.

Each model has different pickups, and the price generally follows the quality, but like I said above, build, woods etc all come into the cost.

My advice would be: for big aggressive sound, get a Classic, which should have a 500T p'up. For that superb self-tuning (including alt tunings, like Drop D etc) get the Robot, and for everything else? A Standard.

Although, I'd get an SG GT (I did in fact )