Upfront my bias: I use three Rollei TLRs. Many times I've been amazed at the detail in my negatives. Recently, I photographed, handheld, a guy at rest with his bike. From 10 - 12 feet away, I was using ACROS film, EI 200, developed in DD-X. On the negative I could easily see thousands of his leg hairs. Those didn't make it through the printing process at my local shop. The scan [300 dpi, supposedly] is too low resolution. I don't complain; prints [proofs for me] are 60 cents each [6"x6"]. I'll see those details when printed with enlarger.
My Rolleis are all 3.5 lenses; Tessar and two Xenars.
I would love to say Rolleiflex (which I own, shoot and love), but I would have to second all the Mamiya 6/7 votes. I love the look of Plaubel shots (I saw a Wim Wenders exhibit last year that was shot almost exclusively on the Makina 670 and it was awesome), but I still think the Mamiya 6 is sharper.
"There is a time and place for all things, the difficulty is to use them only in their proper time and places." -- Robert Henri