Just going to brainstorm on this thread for a bit. If I were creating an ideal set of top 20 witnesses, they'd include:
At least one account from each of the 6 occupied continents
Accounts with keys held by folx who were not majority men
Accounts representing photography, writing, video, dev, economics, homesteading, gaming, and any other content-based communities with a significant population on steemit
Accounts run by people with varying amounts of time on the platform, and that there would be some turnover regularly, so new voices could get heard, but also so that people with experience would be able to guide the new ideas with wisdom gotten from experience