I take the "Guitar-Whisperer" approach to new instruments. Sit down and try different guitars. Don't sit down and play "Stairway to Heaven" (a sin according to the 11th commandment) or your favorite metal song... play whatever comes to you... let the guitar "tell" you what to play. Buy the one that makes the horns pop out of your head and makes you want to crush something.

For a more helpful suggestion... humbuckers are better than single-coil for metal (my opinion)... thin neck, low buzz-free action, etc. I don't know if this was mentioned, but pay close attention the the finish in the neck... go with whatever gives you the lowest friction as you move your fret hand up and down the neck... this is really a matter of preference and playing style.

-Ryan