Are you looking VSTs that perform any particular function?
Drums and synths / maybe an organ? Reverb is a priority as far as effects.
Native Instruments Komplete. There's no reason to do anything else. Especially as they've now opened their parameter world such that anybody can plug into Kontrol. I may ditch my long-beloved K2500XS to get their 88-key controller. The best bang for buck in 'verb is Liquidsonics Reverberate. It'll read IRs from Waves or Avid; I have a bunch of nice IRs from a company that's quite dead that I can give you. For 'verb that sounds like nothing else and is super-stupid cool, you can't beat Eventide Blackhole, which costs a bit, but a lot less than Altiverb XL. Full disclosure - I beta-test for Liquidsonics and Eventide, but there's a reason for that. If you want realism, you need a convolution reverb and Reverberate is the cheapest and best. If you want crazyness, there has never been a company that could beat Eventide. I say this owning Altiverb XL, and having owned 2 480Ls, a System 6000, a KSP-8, an MPX-1 and a half-dozen PCM-81s.