I agree that Dell membrana keyboard is the best membrana keyboard... Not kidin... =)
But regarding mechanical keyboards, I like the one that is lighter to press (red, blue, brown switches). I am old fashion dude that does not know anything regarding the new color switches (speed, gray, etc, etc).
Regarding brands, I think that it is not relevant...Only the switches brands... IMHO, Gateron, Cherry, Outemu swtiches are the ones that I trust. =)