I'm really NOT trying to start a side-thread here, but I would imagine the difference between the most *SOLD* DAW and the most *USED* DAW would be considerably different.
That being said - I would imagine differing versions of Pro Tools would be the most *sold* DAWs around.
I'm sure you realize that the answer to this question in no way represents what the "best" DAW is, what the "best sounding" DAW is, or what the best DAW for you is.