This is almost mission impossible, should you choose to do it. My 1st thought is that there is no good way to go about this. To do it analytically would lead to favoring coaches that have been around longer, or if you created a list across all worlds, favor coaches that have play in multiple worlds. What about coaches that enjoy playing in tough situations or doing rebuilds? Certainly their winning % would be lower, but some would view them as doing "less with more". Theres also the issue where some worlds/divisions/conferences are just much easier to win than others.
To do a poll, would also favor coaches w/ multiple teams in multiple worlds. I've never coached in IBA, Naismith, Smith, etc... If you're strictly in those worlds, you have no idea how good/bad I am. Conversly I have no idea if you're any good or not beyond looking at your record.
Personally, I think the only way to go about it, is by panel, using multiple active coaches in each world/division. Coaches that can be subjective and have an understanding of the history of the worlds and conferences they compete in. For instance, in D3 Wooden, in the Upstate conference there are sub .500 teams in conference that would easily win or finish 2nd in many of the other conferences in Wooden. Its a slug fest every season. I'm sure there are other conferences like that, conferences where no one thinks they have any shot to go undefeated in conference play no matter how much talent they have. Some conferences are mostly simmed or filled w/ bad coaches, such that 1 great coach can dominate season in/season out and rack up 25+ win seasons. Its going to take some subjectivity, and probably leaning more towards postseason success in order to come anywhere close to ranking coaches w/n a world/division.
It would be near impossible to seperate multple alias for some coaches, while others you may have no idea how many accounts they have. I can't look at vandydave/duke and not think the same person, I'm sure some are the same w/ OR/Ryan, perhaps myself and my 2 (formerly 3) accounts, etc...
At any rate, good luck with this, it will take a ton of time no matter how you go about it, but certainly entertaining once someone gets the 25th spot and someone else says "yeah, but I've done more than that guy, and here's how..."