First, I must say that I do not have enough experience with technical cameras in medium format to be able to compare bokeh produced by large format lenses to the mix of medium format digital SLR's I have owned. If you are interested in technical medium format cameras, I would recommend adding these to the mix of lenses you will want to test.
For bokeh, I think you will find that the Rollei's Schneider program will provide the highest consistent quality. Note that I am not talking about sharpness, but quality of bokeh, with smooth and relatively feature-free circles of confusion.
Contax' Zeiss lens program generally delivered excellent bokeh as well, placing second to the above.
The hardest lenses for me to qualify was the Phamiya lenses. Some were spectacularly sharp (eg. 80), but did not impress me with the quality of the rendering--they did render a somewhat clinical rendering. Very subjective stuff, so be sure to try these lenses yourself. Overall I would place these next in the ranked list.
Finally, neither the H or the V systems provide competitive bokeh unless the lenses in question are used wide open. Once stopped down, the V and H are not particularly smooth, with 5- and 6-bladed apertures providing distinctively shaped polygons of confusion. Wide open, I would recommend V bokeh over H, stopped down, the reverse. But because of their stopped-down performance, I would place these last on the list of systems I've owned for this particular attribute.
I have not owned a Pentax, Bronica or Fuji GX680, so I cannot comment on these.
These are my ranked opinions of bokeh based on the systems that I have owned. Note that if you had asked for sharpness, reliability, availability, value or some other quality, the order would almost certainly change, so please do not misinterpret these comments and rankings to be anything other than one person's subjective rankings based on (careful) observations of bokeh quality.
Hope that is helpful,