I think browns are honestly one of the best switches for o!m
I used the QuickFire Rapid w/ Browns, and it was my first mechanical keyboard. I like it the best because it gives that tactile feedback, and you don't get the sound problem that MX Blues have (which i'll explain later).
I also have a Nighthawk x7 (Blues) and like mentioned earlier, you do feel a slight delay since its NKRO (however, it's really neglegible if you don't try other keyboards with it.) The problem i have with blues is that sometimes the sound of the keycap and the sound of the tactile click of the switch tend to make a similar noise in your head, so you feel like you need to hit notes even earlier. (This won't really be a problem if you don't bounce your fingers on the keyboard).
I tried Blackwidow Ultimate 2013, and I like this blue for some reason. I felt like the "delay" feeling on the nighthawk wasn't existing on the blackwidow. Idk.
I tried out a couple of filco browns, and my friend's custom black/brown/blue keyboards.
Browns were generally nicer at firsthand. Blacks were weird... but i guess if u like reds, you wouldn't mind blacks either (but it'd be heavier to play.)
I tried out some MX Clear keyboards, and that is o!m's nightmare. You don't want to be playing on those LOL. I literally played a stamina song with that, and.... yeah... have fun with that. (They have a high upward force, so the keys constantly feel like they're pushing up on your fingers while you're playing.)
I also have tried doing mania with those old cherry keyboards and Model-M's and that was an interesting experience. (way too stiff in my opinion).
Also topre switch HHKB.
I have yet to try some reds. (i don't really like linear switches, so idk. but they should be light to touch, which makes it nice to play o!m.(but u don't get that tactile feedback) haven't tried whites, alps-switches.
I do admit, it does take time to get used to mech switches. not only because of midway vs bottom-out activation, but also because of keyboard sound vs headphones/speaker sound association.