I have used SONAR all versions, Pro Tools 12, Studio One 2, Cubase SX4 I think, Reaper (whatever the previous version was) Digital Performer (can't remember which version) and of course the old Pro Audio 9, and Guitar Tracks.
I currently own SONAR Platinum, Pro Tools 12, and Studio One 2.
I used Cubase when I was taking audio engineering classes at a local college. I used Digital Performer when I was hired to come in to the band's natural environment and produce on site.
I used reaper when working with a long distance client who insisted on it.
I use Pro Tools on occasion just to see how it operates, to stay current and competent with it, and to transfer Pro Tools sessions that come in from clients over to SONAR for mixing and mastering.
I received Studio One for free from a sponsor of a corporate client. I tried it out and didn't like it so I never reinstalled it on my new rig.
I use SONAR because I absolutely love it. For me it completely disappears as a tool and kind of becomes an extension of my mind. It works how I think and sounds great. So it is what I choose to use, even after having so much exposure to so many different DAWs.