This is a pretty close race to be honest. Although Bayern are the favorite from what I've heard, Chelsea are a good put together team when they need to be, and if Hazard is healthy and Ba is in form, they have some striking force. Athletico holding Barca to one goal over 180 minutes is beyond me and has to be recognized. Madrid with a Ronaldo injury could be looking at some tough road ahead, but with Bale, Di Maria, and Isco in form, and their defense holding up strong, they could be champion competitors.
I could see Real beating Chelsea or Athletico without Ronaldo, but Bayern? You need to be at your best with your best players at this stage, as PSG will tell you.