[ysf]

Here are the ones I use most:

Lennar Digital Sylenth 1 (Very fat sounding, cool arp)
Superwave collection (P8, Tarkus, P80, etc....Think Jupiter sounds)
Gforce Imposcar
Vember Audio Surge (many synthesis types)
Rob Papen Albino 3
Novation Vstation
Arturia Collection

There are a ton of great free VSTis at KVRaudio.com as well.