For me it's between Yogi and Neilson and it's very difficult to choose between them. McInnes has done an outstanding job but with much better resources than Yogi.
Despite Hearts going into administration they have made some pretty class signings this season, Sow, Zeefuik, Keatings, Ozturk, Eccersley, Buaben, Gomis. These are all players who are more than good enough for the SPL and so maybe we should've been expected that Hearts would dominate that league, but the style of play by which they did it means no-one would grudge Robbie winning the award.
Yogi meanwhile has had nothing to work with. He inherited a squad which everyone thought was already playing above themselves, only to change the style of play (which is a massive risk when the team was already playing well under Butcher's style) and make the team better. The semi-final was the cherry on the cake for me. Even with the ref decision taking the shine off it, our short passing game was ideal to take advantage of having the extra man and IMO we haven't got the credit we deserve for beating Celtic by being brave enough to get on the ball and pass it.
Hard one to call, Neilson building a squad and implementing a good style of play whilst dominating the championship vs Hughes working with what he was given and implementing an attractive style of play, finishing 3rd (fingers crossed) and winning the scottish cup (fingers crossed).