Since trading McDavid would be a treason against the Oilers and Canada in general, and since only a bunch of desperate teams would consider paying a lot for RNH, Draisatl makes the most sense.
1- His value might might never be as high as right now.
2- Just like Crosby before him, I'm pretty sure you could put almost anyone on the McDavid line, and he'll produce like hell.
3- You can't roll a stacked first line and have a bunch of losers everywhere else, that's dumb as hell.
With Drai, you target teams like Tampa Bay, Nashville, San Jose, etc, and ask what d-men are available. You probably could get a monster package for him.