165s are way to long for 36ers. I agree with the comment that if 150s are too tough for you go for a 29er.
Years riding a 36 I have found 137s to be ideal and most versatile, but it takes some time and practice to get used to riding up steep hills and mounting. In fact lately I’ve been having some issues mounting when I didn’t before. Probably because I am getting old.
But generally I almost never move to my 150 holes on my 36 unless I know I’ll be mounting and dismounting a lot or going on some rough off road.
If you can spin longer cranks, you retain the leverage when you need it for ascents and descents. If you rely on shorter cranks, yes, you can spin faster, but the leverage simply isn’t there.
I rode all 3 of my 36ers on 150s for many years. Recently I’ve been on 125s. Slightly faster and smoother, but I have to be more careful on descents.
Everyone needs to find their own balance according to experience, needs and taste. Someone like Aspenmike who does (used to do?) 3 mountain passes before breakfast probably needs long cranks. Someone who teararses about on the flat may ride on very short ones. As I tend to mix road and off road on the same ride, I go for medium to medium-long.