Nice poll, Flowers! Analysing business plans is part of my job, so I'm kind of in my element here.
First of all, I think this contest is really only between Mana and Kisaki because none of the others are running their own companies, so they don't really qualify as businessmen. They may have some degree of influence over their fortunes but they have effectively handed the reins of power over to their respective labels. No matter how successful they are, they don't decide on business strategies and they don't plan their own budgets. They have less responsibility and face fewer risks than Mana and Kisaki but they don't reap the full rewards either.
Mana and Kisaki have a lot in common: they are both successful businessmen and have survived in the cut-throat entertainment industry for +/-10 years. They have done so within an obscure niche of the Indies scene and stubbornly refuse to compromise on their artistic ideals for greater commercial success. Both have faced serious setbacks in their careers but have emerged stronger from the crisis. They both own their own music labels and were some of the first Japanese Indies artists to expand internationally.
But there are differences as well: Mana is not only a musician but also a fashion designer and owns and successfully runs not one but two companies (Midi:Nette and Moi-même-Moitié). Kisaki has always been Indies whereas Mana took MM to a major label and then moved them back again to his own label. Kisaki's previous label, Matina, folded whereas Midi:Nette seems to have always been doing OK. Undercode has several bands (as did Matina) whereas Schwarz Stein was the 1st non-Mana band that Midi:Nette ever signed.
Here is a quick comparison:
Mana:
Own music label: yes
Own fashion label: yes
Number of bands on label: 3 (1 active, 1 on hiatus, 1 disbanded)
Domestic release CDs/DVDs/VHS: 50+ (MM, M10M, SS)
International distribution (CD): yes
International distribution (clothes): yes
International website: yes
International fanclub: yes
Foreign release CDs: 2 (1 M10M, 1 MM)
Foreign release DVDs: 1 (M10M)
First live played abroad: 3/2005
Number of lives played abroad: 2 (M10M)
Kisaki:
Own music label: yes
Own fashion label: no
Number of bands on label: 6 (active)
Domestic release CDs/DVDs/VHS: too many to count^^
International distribution (CD): yes (Kisaki Project & Vidoll)
International distribution (clothes): no
International website: no
International fanclub: no
Foreign release CDs: 2 (1 Kisaki Project, 1 Vidoll)
Foreign release DVDs: 0
First live played abroad: 6/2004
Number of lives played abroad: 2 (1 Kisaki Project, 1 Phantasmagoria (upcoming))
Overall I think Kisaki's performance as a businessman is more volatile than Mana's. Perhaps Mana is able to be more constant and more focused because he essentially only sells one product (himself) whereas Kisaki always had to look after a whole bunch of bands but having more bands also spreads the risk (i.e. if one band messes up you still have the others). Mana has almost always had all his eggs in one basket but he has never had to close down his company like Kisaki. I have no idea how they stack up against each other in terms of domestic CD sales (probably even?) but Mana seems to be selling more CDs internationally. Kisaki was first to go abroad but Mana has achieved greater success in a shorter period of time, M10M being the second most popular Japanese band in Europe after Dir en Grey (by concert tickets sold), and he was able to achieve that with only 1 active band. He now has a bi-lingual website for his band, sells his clothes internationally and is one of the very few Japanese artists who have an international fanclub.
So my vote went to Mana.
[EDIT] Added more detail to stats.