How much effect the type of wood/construction will have on the sound of an electric guitar usually is only noticeable on low output single coils. With low-output single coils, the sound is relatively "transparent" and detailed. Typically, this will be more pronounced in hollow body and semi-hollow guitars than in solid body guitars (though the wood of a solid body will have some difference, particularly with low output pickups, but it's pretty minor). And the expense/rarity of the wood isn't a big factor (Danelectro notably uses what's basically plywood, and they sound amazing) so much as the density - and even then, it's personal preference.
Regardless, with metal, none of this really matters. When you're playing with high output pickups and lots of gain, there is no transparency and detail. You're basically going for sustain (which is also achieved through gain) and high output (which lends itself to more gain). The very nature of metal means that you're driving everything so hard that any nuance between guitars becomes irrelevant to the sound produced/is buried by output and gain. In terms of sound, it's pretty much entirely the pickups and the amp (able to saturate/drive with that high output). Nothing else really matters in terms of sound (though players may have preferences when it comes to playability - shape of the neck, fret type, scale length, string thickness, etc...).