Well, the stuff that gets a lot of use from me these days is Kirk Hunter Concert Strings II, Concert Brass II, Damage (big drums, percussion, distorted elements), Impact Soundworks stuff, the old Kontakt EastWest libraries (not so much these days), some of the factory stuff (orchestral), and various and sundry other 3rd party stuff I dinnae remember.
Throw in Omnisphere (my fav), Engine2 libraries, and a few elements from Sampletank 2 and you basically have my setup.
Problem for you is, most of the stuff on the list I purchased on sale, so buying it all now would be prohibitively expensive. The best entry-level bulk sounds are either Komplete or Composer's Collection.