As a metal player primarily, my take on gain isn't the amount of it but the quality and the filtering. I much prefer a lower gain, more toneful sound, to sheer chainsaw nightmare levels of gain that just compresses the heck out of the tone.
Mesa Mark amps allow you to do a lot of the filtering and gain staging on the amp because the lead channel has 3 independent gain controls. Volume 1 controls the input amount, Lead Gain controls the amount of saturation, and Treble controls the filtering and incremental gain staging.. So you have a high quality gain signal with the ability to filter it however you choose.
Then there's 5150s, SLOs, and Rectifiers. Amps with a ton of gain on hand, but you are somewhat responsible for your own pre-filtering. I prefer these amps ran with the gain lower and an overdrive out front, which gives a ton of freedom to shape the filtering how I choose. The amps' controls give enough function to sculpt a sound but it never deviates from the core sound of the amp. So you get a super harmonically-rich gain sound that blooms or cuts when you stick different overdrives or EQ boosts in front of them.
Some amps just have a ton of gain. I love the sound of EVH heads, but that red channel is basically a distortion pedal and I always wind up putting a 12au7 in place of the main channel 3 driver just to knock the gain back a bit and make the gain knob more usable.