FlixTrain 

I’ve taken a ride on the Cologne to Hamburg line. In comparison to Deutsche Bahn the ticket was pretty cheap. The service is a bit inferior though I feel. I couldn’t succeed to connect to the wifi apart from a short period of less than a minute though trying on three different devices and two different operating systems.
Unfortunately the schedule on the ticket doesn’t give information on the platform. I could find a bitly short URL redirecting to a Deutsche Bahn page with incomplete platform information. That’s complicated and bad for data privacy.
Public loudspeaker announcements in the train very pretty frequent and partly completely irrelevant admonishing behavior of some individual passengers publicly.
Considering the comparatively affordable price anyway a good option.