I had always used roughly 690mm bars with a 10degree back sweep and found that OK.
When I then moved to using 745mm bars with 10degree back sweep I started developing pain in my wrists over a 6 month period. I tried to go back but from then on I still had pain even with the old bars.
I then tried some Mary Bars 680mm-ish, 40 degree back sweep. Although this solved my wrist problem, I felt that the back sweep was too much and I found them very twitchy off road.
So then I tried the Salsa Bend 2 bars 710mm with 23deegree back sweep and at last found what I was looking for. Wide enough to get a good feeling of leverage but with enough back sweep for my wrists.