You mean which VST do I like best right now? If I could only keep three, it would probably be:
Dune
http://synapse-audio.com/dune.php
Zebra2
Sylenth1
In that order, but that depends on what kind of music you want to make.
If nothing else, spend 10 mins or so with the Dune demo. Programming it will feel right at home after the Virus.