I was using Cool Edit, then recently used Reaper for several months, and now I might switch to Sonar 6 or 7.
Reaper's limited MIDI capability (namely tempo changing within a song using VSTs) is forcing me to switch. Brings a tear to my eye to have to let it go over something as small as the inability to trigger tempo changes off the grid (ie free form). I need it for my music though.
If Justin decides to fix this, I'll be all over Reaper again. I spent a lot of time already learning the ins and outs of the program, and it sucks to have to start back at square one and learn a new one.