Red: 30g linear ("cloud of boobs")
Brown: 45g tactile almost-linear ("red, but with a grain of sand")
Blue: 55g nonlinear, clicky, tactile ("loudest / most gimmicky")
Black: 60g linear ("heavier red / silicone boobs")
Clear: 60g tactile nonlinear ("heavier brown")
In my experience owning each of these keys, Browns are the best multipurpose switch for people who do a solid mix of gaming and typing. So for most people, I'd say to just ignore the rest of the switches and go straight for Browns.
I like Clears for CS:GO (highest MM rank Supreme) because the switch makes a solid effort to resist the pressure of your finger, so it's hard to accidentally move in high-pressure situations by resting your finger on a movement key during high-pressure combat.
I like Reds for Osu or any other game that requires repeated taps of alternating keys, and and they're the second-best all-around switch for me (after Browns) after getting used to their lightness for typing and adjusting accordingly. Browns still beat them for the typing experience, though.
Blue is a good typing-only switch if you don't mind annoying people around you with the exaggerated loud clacking (granted, they're not as loud as old-school IBM keyboards, but significantly louder than other Cherry MX variants).
Blacks are my least favorite key right now. They're kinda in a weird no-man's land. Clears are a better switch if you're looking for something heavy. By the time you want a linear switch, you probably don't care about the weight all that much, so Reds are better for that use case.
