Kind of hard. Not in a way that "which is better", but in terms of finance. McDavid hype is going to bring in so many cash if it works out (maybe not for long-term, but it may very well go on for a certain period of time).
In terms of hockey value (not financial), than its definitely Eichel and Hall. Hall can be a top 10 scorer and has proved that last season on a terrible Oilers team, while Eichel might not be McDavid but is darn close (he would be 1st overall on any draft aside of Crosby and some couple other ones), and has that physicality factor which McDavid doesn't (not saying McDavid doesn't have any physicality, but compared to Eichel, no).
This is probably unlikely, but McDavid could bust or underachieve. At least one team can secure a player that is capable of scoring top 10-50 in NHL scoring on a consistent basis.