If you REALLY want the "longest lasting", skip the soft kids stuff "membranes" and go all in on a once piece ALUMINUM roof.. Most likely it will out live you.
Aluminum roofs got a bad rap from being much more expensive and often when RV companies cheaped out, they would just piece together short sections instead of buying a long one piece roll..
All of the soft roofs will tend to fail every 10-15 yrs and need replacement often..
Now days kind of tough to find anyone willing to ship a big roll of aluminum, will be truck freight, will be on a large skid and will need some means of meeting up with the truck and get it off the truck safely..
You asked for a "better" opinion..