We prefer to travel on Condor from BWI to FRA but it is seasonal so we don't always get to fly them (had to fly WOW last week). But all of our flights to and from FRA have been good. We do prefer to book the premium class (premium economy) so that we get the extra legroom and the free (included with fare) IFE.

As far as not getting seat assignments FRA to MUC it is a very short flight so I would try not to worry too much about it.