For me the 86 is written off just because the stock plastic panels make it too thin, and the hogues dont actually fit the gun right like Dio said a few posts back. The spacing near the trigger guard is off and it makes it really uncomfortable.
The normal fatter .45 is perfect and there are a lot of great grips to choose from. I would probably prefer the 86 frame if I had some wooden panels that fattened up the frame. Some guy here makes them. That would work for me.
On a gun with a back block I would ALWAYS choose a 45 frame. With the 86 you are tucked in too close to the back of the gun where the back block will want to contact your mask all the time. There are ways to shorten the length of the gun out the back, but to keep the back block bolt and cocking rod out of your face a little bit, I would definitely go with a 45 and maybe even a drop backward depending on the tank you are running.
On a T2 or S6.5 that isn't an issue.