You’re seeing more Viking ads because they spend more on marketing not because they’re the only river cruise option.
There are quieter luxury river cruise lines that focus on space, service, and inclusions instead of advertising.
If you’re planning your first river cruise, don’t choose based on the loudest ads. Choose based on fit.
Here’s the link to my River Cruise Preview Guide where you can grab a side-by-side comparison of three luxury lines:
https://stan.store/travelbytarab