The world is full of great drums. Why is it that most drummers use the crappy ones? We all know the answer: money. Good drums cost money. Different woods have different sounds. Most quality drums are made of either maple or birch. Maple has a warm and smooth sound, while birch is brighter and has more presence. One thing to keep in mind is that the thickness of the shell affects the sound very much. You want the drummer to hit hard, so choose a shell thickness somewhere between medium to thick (6-10 ply).
Placement
Toms should not be attached to the kick drum! It will affect the kick drum sound in a bad way. Set the toms as flat as you can. Not like Lars Ulrich did in the 80's. It will improve the sound a lot. The stick will hit the head at a smaller angle and you will get more power. Just make sure the drummer isn't hitting the rims.
Most metal drummers use 20 and 22 inch kicks. They're both fine and sound good recorded (though smaller kick drums make it easier to place the toms). One thing that affects the tone of the kick drums is the material of the beater; it can be felt, wood, plastic or rubber. My favourites are felt and wood, but experiment with different options if you have the chance.
How about toms? Let's put it this way: toms on Derek Roddy's kit: 8", 10", 12", 14", 16". Toms on Vinnie Paul's kit: 14", 15" and 18". You get the idea. Smaller toms have better articulation. Same goes for the depth. Deeper toms have more volume and power. The problem with deeper toms is that they are harder to set flat.
You will get the best results when the toms have at least two inches difference in size between them. The tuning will be much easier. A one inch only difference will not be enough. For some unknown reason, most old drum sets have 12" and 13" toms. This is not good.
You can find even more options when it comes to snare drums. My favourite material is metal (brass, bronze, steel, aluminium, etc.). It sounds brighter than wood and to me that's a good thing. One of the most popular snare drums in human history is Ludwig Supra-Phonic (aluminium shell) and there is a reason for it.
How deep should the snare drum be? Most of the time 8 inches is too much for extreme metal. Anything below 8 inches will work fine. Even piccolo snares (14"/3") can have a full sound. If the music is very fast, you want the snare drum to react faster.