Orchestral has a lot of VERY good quality (at least IMHO) voices, but they will suit o someone that makes soundtracks, or classical music. The piano is superb. It is not GM/GS compatible.
Super Quartet is Keys, Bass, Guitar and Drums only, it has some nice sounds and the drums are much better (again IMHO) than the Hypercanvas. Of course you can add a second guitar or another "keyboard" in this virtual band but it lacks synth sounds and distortion-overdrive guitars. Not GM/GS compatible.
The thing that makes HyperCanvas good is that is has an good quality all around and the intruments are blending very well together. For lack of a better word, they all "belong" together. And of course they are GM/GS compatible.
Hope it Helps