I have mostly used MX Reds for gaming for a little over three years with no complaints; I've never found them tiring. I recently put blue WASD o-rings on them, and I like them even more now. It makes them a tad mushy upon bottoming out, but it really improves the typing experience overall. The o-rings haven't affected games much as far as I can tell; they do reduce travel a bit, so that could be a plus if you need really fast key presses. I will say that the MX Reds also suffer a bit from scratchiness too, but it's not something I noticed until I started reading about it.
I don't have any experience with Gaterons, but I have heard they are smoother and lighter, so they might be a good choice (clears, reds, or blacks). I have some 67g Zealios, but I haven't put them on anything yet, so I can't give a valid opinion on them.
Recently, I've been using Matias Clicks for games, so maybe my opinion isn't that great, lol.
TL;DR MX Reds are decent, but they are basically slightly lighter blacks.