I have:
Sonar Platinum (My go to DAW) - I use this for tracking, mixing, and mastering. See below comment about mastering!
Studio 1 Artist - Never use it. Tried the New version 3 demo and could not justify the $99.00 to upgrade.
Harrison Mix Bus (The cheap version). - I just got this and so far I am liking using this for mastering. It seems to have that "Special Sauce" that mastering provides. I import my two channel mixes into MixBus and apply very little (sometimes no) processing and the output is very nice!
Just my 2 cents.
I have looked at Tracktion, Reaper, Audacity and other low budget solutions and I just keep coming back to SONAR. It is what I learned on (Since Pro Audio 9) so it is what I know best.
I am a hobbyist with limited time, so I am not spending 8-24 hours a day with it, but I do have a few hours under my belt...