The bare minimum for an awesome tone is an awesome guitar player, fresh strings/decent guitar setup, a kind of good amp / amp sim, and a boosting pedal (like a TS). Cab is important too but mainly for the tonal characteristics and behavior.
Noise gate isn`t a must, same with compression and equalizers. You need noise gate if the guitar player plays like shit, if the amp you chose is really noisy even on not-so-fucking-super-high-gain-settings and if the genre calls for it. But nowadays it is quite common although it makes guitar playing feel like shit on high settings.
Compression is needed when you have a high gain tone but the amp is still dynamic as hell which isn`t the case with most metal amps (especially not with free amp sims). Or if the guitar player`s picking hand sucks, you might need it again but it is a trade off as it thins out the guitars low end. So I would try to avoid single band compression on high gain guitars but it is up to your ears and it is up to if you know how to use it.
Equalizer is your go-to tool when something is odd within an awesome tone and you can`t get rid of it BEFORE you record. With metal guitars this is often the case but try to avoid using too much equalizer because let`s face the truth: one can hear the equalizer madness on high gain guitars very well and it makes the tone sound like shit.
Generally I think I can make any tone sound cool by just playing the guitar according to what I have. It may not suit the genre or a certain part but the tone will sound cool on its own so it is really hard to talk about tone without a context. I just wanna point out that the best weapon to a great guitar tone comes from the guitar player itself and that`s the case with any organic sounding instrument. And it applies to amp sims even more as they do not help to sound better at all. In fact, I find them to be even more honest because of their sterility.
Also: Everything that agentmetal said. :]
EDIT: "kills witch" made me giggle quite a bit.