I chose Viking as I had never been on a river cruise (but have had 4 ocean cruises) and I wanted to see the Passion Play. Also, the last 5 days in Bavaria were spent between the two families of our 1998-99 exchange students; our last visit was in 2000!
Planned my trip through AAA of WA - excellent service and updates! Viking handled flights, people available to ask questions and get assistance, transportation, comfortable hotels with great restaurants (all breakfasts and most dinners included, plus lunch and snacks before & after dinner on the first day we boarded the ship).
Viking has fewer people and staff knows almost everyone by first names.
Not sure which category but had French Terrace staterooms - basic - which is what I wanted. Clean, cared for, passenger comfort was provided and honored. Personal service was the key without being overbearing or 'forgotten'.