Re: I have $600 to spend on a guitar.
Here's what I do: Get a used set neck Epi LP ($300+) or SG ($200+) online in excellent condition. Put in a pair of SD's, DiMarzio's, or Gibsons (about $100 for a used pair, more if new). For $300 to 400, you have a guitar that sounds so much like a Gibson, VERY few people could tell it apart on sound. Spend more if you want, but you don't need to.
OR........If you go the SG route, get two G-400's, and put hot ceramic magnets PU's in one for metal songs (Custom, DD, Dual Sound, 496R/500T, etc) and alnico mag PU's in the other (JazzN/C5 or a pair of '59's) for classic rock. You can do this for about $600 total and have two great sounding guitars. The ultimate versatility.
Get a Gibson & you may want to replace the PU's, like SO many guys do, and your costs go over budget.