I find the Bronica GS1 prism finder with split image focusing to be the easiest and fastest to focus out of my medium format cameras. The Hasselblad is by far the hardest and the Rolleiflex is almost as easy as the Bronica. I think theres probably a 95% success rate when it comes to focusing using the Bronica prism finder, but its heavy as heck and bulky. You cant have it all I guess.
Photos taken by Bronica GS-1 camera and Kodak Portr, Kodak TMax 120 film.