For strings: Audiobro's LA Scoring Strings or East/West's Hollywood Strings
For brass: CineSamples' CineBrass + CineBrass Pro or East/West's Hollywood Brass
Nobody's really done an in-depth woodwinds library so far. (I guess there's CineSamples' HollyWoodwinds, but I haven't really heard anything that uses it.)
For what it's worth, LA Scoring Strings and CineBrass generally sit really nicely together in a mix. So if one of those libraries piques your interest, I'd suggest complementing it with the other. Hollywood Strings and Hollywood Brass sit well together (they were recorded in the same hall).
I wouldn't advise mixing LASS and Hollywood Brass, or CineBrass and Hollywood Strings: the results will certainly still be very good, but you'll have to be really careful about the reverb you apply, or it will sound like your strings and brass were recorded in two entirely different locations. It's pretty subtle, and most people probably won't even notice it.
But I will.
If you want a kind of broad library that gives you a lot of content for your money, you can get East/West Symphonic Orchestra silver or gold. The difference in sound quality, versatility, and realism when you compare that to the newer, more expensive libraries is very noticeable (Symphonic Orchestra is fairly old as far as VSTs go), and it's nowhere near as in-depth as libraries that focus in on individual sections, but for the money it's a pretty good deal: you get woodwinds, brass, strings, and orchestral percussion all in one library.