I can see that this post is a few months old and you still got no answer, sorry about that!!!
The easy and cheap way is to get the Vst complete collection from Steinberg. It is superb for all kind of music and you will not need anything else for a very long time. I have it my self and I have to say that there is many new vst´s out there, no one is better than the vst collection. If you would get any thing else it would be new patches to mess with, ones you can easy make in Halion.
If Steinberg is a no go then there is:
East west
Kontakt
Omnisphere
Falcon
All of them nice but not better or even as good a choise 
And no I have no relation to Steinberg, I just work with it every day 