Truth is none of us really know anyone, so giving names bar Van Der Sar makes not too much sense.
However, we can state the type of individual we want.
For me, I want someone with a clear understanding of what United is as a football club, preferably person that has worked with or against the club and therefore understands the cultural struggles, the transfer struggles and the negotiation struggles we have had since 2013. I would like someone who is more hands off in terms of the football side and is rarely and tries not be in the public eye. The most important challenge is ensuring that United's football side has the right support it needs without seeking glory or bragging, just simply keeping things as professional as possible, which is also part of United's culture ironically. It's important for this figure to keep the board away from the football side of things, like both Gill and Woodward did, without being a distraction themselves.
United aren't like Bayern where the board members constantly fight and take attention away from the team. We need to operate like we did under Gill, professional and out of sight....ironically, like City's are now.