My preference is for an adjustable rib and a fixed comb on a custom stock that fits. Comb height should be high enough so that with the front bead in the lowest position you are looking straight down the rib (buried beads). Why? I'm not bothered by all that figure-8 crap, so an adjustable rib gives me all the adjustment I need without having to move the comb. Just remember to move the bead in the opposite direction you want the shot to move.