I really do think I'd give it to Ole. There would be feel-good vibes, the fans would be on side, and we'll get that bounce in the league which might be enough to finish 6th. But it would be more about the FA Cup Final - he has a decent enough record against Pep and could set us up in a way to have a chance in that match. To me, the reason you change the manager now and not at the end of the season is to win the FA Cup. Because I don't particularly think we can beat City playing the way we are playing, and I don't foresee EtH changing his gameplan for the final.
Unless the manager they expect to be the next permanent manager is already available, then you need to pick an interim to be exactly that. Ole is extremely logical and the mistake of giving him the permanent role wouldn't be repeated.
Mourinho is another option, but I just don't see that calibre of manager (even if his stock is at its lowest) taking an interim job anywhere for just a handful of games. I think someone like Ole would as he is after his next job and maybe wouldn't mind jumping back in to something short-term to dust off the cobwebs.