I would bet on Mourinho personally. Guardiola is still a big unknown in my books. I think Moyes could have managed the Barca and Bayern sides Guardiola had and still done quite well. Its the same with Blanc at PSG.
Bayern are ridiculously well run from top to bottom. They have 1 half competitive side in their league and every season they plunder them for their best players. Geotze, Lewandowski and Hummels have all contributed to a massive swing in Bayerns favour.
Barcelona are one of the top teams in the world, have a team full of superstars and a player who is on another planet to everyone else playing the game.
Mourinho has won leagues, CL etc with squads that are not the best team at that point so I have more faith in him.
That being said, next year will be a cracker regardless of those two. There will be 6 teams with great managers fighting for 4 CL spots. Out of the 6 I would say that Spurs and Liverpool are the most likely to fall short.
Klopp is a great manager but I don't know whether his brand of football will succeed over a full season. Its too intense to keep up every game.