The BEST is what works best for YOU, with YOUR gear, and satisfies YOUR desires ...

You really need to get out and test a few ... the most common mentioned here are the digitech: http://www.digitech.com/
and tc helicon: http://www.tc-helicon.com/VoiceWorks

The fact that you are picking up the music through your mic may have more to do with the mic than with the Ty harmonizer ...
What are you using?

t.