I have only hunted region A once, and that was a long time ago. However I have a group of cousins that hunt it yearly on the same ranch. First access in Region A can be pretty limited, unless you have already locked in ranch access through your antelope hunt. Access for antelope is typically easier to come by than access for deer. Secondly while my cousins are not trophy type hunters, they have been on the same ranch for over 20 years, and while I never taped the heads, I doubt if any of the mule deer they have gotten would go over 150, and that may be kind. There are however some dandy white tails in the area. They hunt in Area 2 within Region A.
I have no knowlege at Region B at all. Depending on your physical ability I would recommend a Region Y hunt simply for the mountain experience and the challenge therein. You will be a better hunter when you leave the mountains than when you went in, even if you leave empty handed. Some of my best hunts are when I returned empty handed, because of what I learned by the mistakes I made.