Disagree about Reus and Bayern. He is a versatile attacking midfielder but his primary position is left winger. Bayern has Ribery there, but Ribery is getting old for a winger (he had a great 2013, but his performance in 2014 was a pretty steep decline). If Reus joins Bayern, he can share the job as a left winger with Ribery in his first season while learning to play the Guardiola way and then take over the season after that. So while Bayern already has a lot of talent in the offensive midfield, Reus would perfectly fit their future needs.
Trophy wise, his chances to win the CL are probably the best in Munich and Madrid. ManU might fully come back next season but you don't know for sure now. I also believe Reus would prefer to win the german championship and cup over other leagues. Reus has't won any national titles so far and I think any player from the big leagues would prefer to win the titles from his home country over the other league's titles.
Real wouldn't really make sense as Ronaldo is too good and too valuable from a marketing pov, so Reus couldn't play on his best position. Real is hard to resist for any player though, so if they really want him only to keep their caroussel of crazy signings spinning, they might make him a good offer.
I agree about ManU, I think they're the most likely team in the PL to get him. Van Gaal is a great coach and I think he likes german players. At least he did a great job developing german players when he was at Bayern, he's imo partly responsible for the success of Bayern in the last couple of years. Chelsea has Hazard and City seems really unlikely too me.
Still Bayern >>>>>>> Real Madrid > ManU
