I prefer keymod as you can also use mlok on them where as key mod doesn't work on mlok
I didn't know this. I've got quad rail and keymod. I went with the keymod over the mlok just because it seems like (for now at least) more companies are making attachments that work with keymod. If I'd have known that mlok attachments work with keymod it might have swayed my opinion some.
I prefer quad rail with a Sh**load of covers for comfort. I've tried them all, but in the end I always end up adding a standard rail attachment to the specialty mount, so why not go lowest common denominator and be done with it?
In a word, weight.
I like the idea of "rail where you want it, not where you don't". It seems backward to me to put unneeded rails on something, then cover them up for comfort.
I have keymod on my DD, because that's what it came with.
I suspect that Keymod will end up the Betamax of this issue: technically better, but commercially a loser.