I am looking for low power polys that produce good spin and keep some control. I like the dunlop black widow, blue gear, yonex poly tour spin. I have found that 16 gauge will give better consistent control but not as much spin as the 17 gauge, anything thinner than 17 and I lose to much control.
I also string any of these polys at a minimum of 65 lbs. Many here will say I am crazy for using that high of tension but I have no problem with it and anything less makes the control not last as long.
Right now I am using gamma powerplay 18 gauge kevlar at 58lbs. with yonex poly tour spin cross at 63lbs. This set up is tremendous but like you I want to get away from kevlar to prevent injuries.
If I find a great poly that does what I want I will let you know, but so far I have found some that do exactly what I want but only for the first day. Still searching and maybe I just need 3 rackets instead of 2 and string more often.
The stiffest copoly on the market is Revenge, so that might be worth a look if you're coming from Kevlar. The best in terms of tension maintenance is 4G, by quite a margin too, and that one is fairly stiff as well. Since it holds tension so well it will play stiffer for longer than other copolys.