We previously cruised the Rhine with another company. Relatives had done the same river with Viking and highly recommended it. We traveled with them on the Heimdal. For my husband and myself, we had been to Paris more than once and wanted to explore more of France.
We did enjoy our Rhine River cruise with another company, but prefer the Viking cruise. Of course, the itinerary was different so a completely fair comparison can't be made, but I will say some of the things that put Viking on top. For one, I would say dinner was better. There were more choices. On our previous cruise, chicken was never an option and it is something that we normally eat a lot of at home. The desserts were better on the Heimdal and the chef who gave a preview of his dinner offerings every night was always so enthusiastic.
The entire staff of the Heimdal was great. This continued with the guides on all the port excursions. The ship was large enough to accommodate people on the deck at all times, even for meals (unfortunately, the weather was so hot we never did dine there).