The Bronica you mention is a very good lens and I've seen beautiful work from a friend's. My guess is that a Rollei, likely a 2.8 Planar would be about as sharp as you could find on a TLR. I had one and it was a great piece of glass. I also had a Koni-Omegaflex back then and the Hexanon 90mm was an under-appreciated optic that was as capable as anything, especially when stopped down but was excellent at wider apertures, too. Some of my favorite old enlargements were done with a Tele-Rollei which was exceptional, also.
I've been everywhere ooooohhh yeaahhhh still I'm standing tall.
Mamiya TLR lenses are excellent, especially the later model black versions. Not too pricey either, especially compared to Rolleis .
"He took to writing poetry and visiting the elves: and though many shook their heads and touched their foreheads and said 'Poor old Baggins!' and though few believed any of his tales, he remained very happy till the end of his days, and those were extraordinarily long "- JRR Tolkien, ' The Hobbit '.