My .02 based on recent research, knowledge of roofing picked up in my day job, and personal uses....
Agreeing with Lauralee - the Butyl Rubber (and EPDM's) will likely be best as far as UV resistance....
EPDM's are used in the roofing industry for membrane roofs due to good UV resistance and durability.
Granted.... they are very different compositions.
How many types of neoprene?
I've seen stuff labeled Neoprene Foam, and Neoprene Rubber, and Neoprene/EPDM
What I can tell ya is I used the stuff JoAnn Fabrics sells on one of my units with a GAST 2.7 CFM 24 in hg pump and it worked fine.
The pump is a Diaphram Pump - Like the HVAC industry uses
The neoprene from JoAnn was a Neoprene Foam faced with nylon on both sides.
JoAnn sells it under their UTILITY category, usually black nylon on one side, and either green or burgandy on the other.
Using this worked fine for me.
I WILL SAY THOUGH, I think it is quite a bit thicker than commercial units use.
I just got a different unit... a SPS Inc unit (Defunct) and it has the same type of pump, but 4.1-4.8 CFM, same vacuum.
The unit has Neoprene Foam with nylon on the top side.
Can't tell you if it is original to the unit or not. No idea.