I bought the non-commercial Reaper because I was intrigued by the idea that a track was anything you wanted it to be (including a bus). That was about the extent of my using it. I could not get behind their paradigm.
I bought into Studio One because of sales. I like the look but I had some troubles with MIDI that I did not want to spend more than an hour on. I have not upgraded to V3. Probably won't.
I bought Harrison Mixbus as a mastering environment. Stopped using the 32bit version when certain 32bit plugins didn't behave. Waited on Mixbus 3. Bought it. Have only played with it for about an hour. Waiting 3.1 when ASIO support is better as well as better VST support.
Pro Tools has zero allure to me.