I took a 30 day demo of Cubase 9 earlier this year. It has a great MIDI implementation, and some cool composition tools like the arranger track and chord track.
If you are mostly into MIDI and/or music composition, this would probably make a great alternative to Sonar. I was primarily interested in Cubase for some new creative tools. But I held off because it seemed like too much overlap with Sonar's DAW features. Didn't really need a a second full blown DAW... well until now, that is, LOL!
If you have a Groove3 pass, there are a lot of videos covering Cubase over there. If it looks interesting, download the fully functional 30-day trial of Cubase and take it for a drive.
I have also tried the free version of Studio One 3 Prime, and it's UI seems easy to work with. I think it would work very well if you mostly record and edit audio. Don't have an opinion on the MIDI usage there, because you can only use VST plugins with the pro version.