It's one of those times where I don't care if it's better, it's so silly looking I could never own one. I am not using a Single Action to defend myself so the need for perfect marksmanship or ability wanes when I contemplate a single action's use. I don't shoot one-handed. My opinion and others' will vary of course.
I'm just opposite, well almost. Yes, I prefer Bisley appearance, and above all, the way it handles, especially with heavy loads. As a matter of fact, some custom smiths wouldn't even build .475 and .500 on any other revolver but Bisley. Presently, I own two Bisley revolvers; one blue 44 magnum, 7.5", also 44 Magnum, but 5.5", stainless, converted from SBH.
As for Blackhawk, nope, not my cup of tea in any aspect. However, I just purchased SBH in 44 Magnum, stainless, 7.5", with Dragoon (square) style trigger guard. Yep, I like it. Not as much as Bisley, but still immanently better than Blackhawk. Hope to test SBH next weeks for accuracy, and if it's good, I will start looking for parts to convert it to Bisley.
As for original grip frame from noted SBH, well, looks like that there is away to install it on Ruger Old Army, without installing trigger return plunger. In that case, I will have much better grip than current one on Ruger Old Army. Just checked; SBH square trigger guard grip is about 1/2" longer. A big difference in handling, even for my medium size hands. But, equally important, SBH Dragoon style grip makes already classy look of Ruger Old Army way classier. Of course, this just "copy & paste" version, but you've got idea:
IMHO, Ruger Old Army is way better with SBH style grip than with BH one.
UPDATE: My "dream" Ruger Old Army, with same hammer spur like on SBH