Most important thing with any tablet is the OS. iOS is the best for any sort of pro music applications in the purely tablet area, not just audio, but MIDI as well.
It leaves the others in the dust. Android is making some efforts, but the issues are inherent in it's OS. So until there is a fundamental change in how Android OS incorporates audio/midi interfacing and operation, then it will always lag far behind.
Any tablet/tablet-laptop hybrid running Windows OS is okay as well...especially 8.1