This also depends on local availability for me anything other than a common sen is rare. In places like SoCal they have good priced and sized polys and can find them pretty easily (at least from what I've heard). IMO Upper jaws go from (I'm going from most common to rarest because for some reason it's easier) Senegal (both albino and normal) CB teugelsi, ornates both CB and WC, delhezi, Palmas polli, palmas buettikoferi, palmas palmas, weeksii, retropinnis, mokelembembe, WC teugelsi. The moke and retro can go either way for me. As far as CB teugelsi I can go down to my LFS and get one ordered in in about 3-4 days. Thats actually how I got my CB teug about a year ago I just walked in said I want one and they ordered me one. WC senegal for me can be a really tricky one though, because of it's rarity and for some the inability to tell and CB from WC puts it after the weeksii for me. This list is basically for my area (However I haven't ever seen almost half of those in my list in one of my LFS).