This sounds kind of funny, but subtractive eq doesnt add up to much with high gain guitars. If your cutting big holes in your midrange to get closer to the sound you want, its likely your tones werent vibing with the mix in the first place. You really want to nail a tone that you enjoy without eq, and then eq just a becomes a big enhancement, not a correction.
You should be able to shelve out the highs from 9-12 and up completely out as well lows 60-75hz and down completely out as well, and end up with a very functional guitar sound. From there its best to find the frequencies you want accentuated, which in most cases is gonna be the frequencies that will help the guitars sit better in the mix. Your gonna find that you want an eq with alot of frequency options, so a 5 or more band parametric eq and or a good graphic with adjustable bandwidth will really be to your advantage to have. You may even use multiple eqs if wanna get very particular.
Its all good! 
