Reply to Ableton VSTs

What are the absolute top VSTs out there. Mainly used for live DJ sets, but useful ones for music production would be good too. Already been recommend NI's Massive.

Also, anyone got any pointers towards setting up quality effect racks in Ableton?

I'll be controlling it with a VCI-100 (crossfade, volumen, loops, sampler), Launchpad (launching clips mainly) and LPD8 (effects) so I'll have plenty of assignable controls for the effects.