Hi
For me, it depends on whether I'm practicing a specific song or composing my own song. If practicing a specific song and performance of it, I usually get the mp3, then bring it into Moises. That application then splits it into different tracks. I then mute the guitar track or lower the volume of it so that I can practice. So I normally don't even use studio pro for practicing on a known performance. I realize studio pro also splits into tracks, but I have had better results with Moises.
I have also heard positive reviews of Jamzone, which produces amazing quality backing tracks, but I have not personally used that.
For making my own original song backing tracks, that's a different story involving Studio Pro and some other tools.