I'm in the Spitfire camp mainly.
On that note, you would need to spend more than 2k if you want that kind of versatility, since every library is strong in a different area and has downsides in another. So:
-Winds: Symphonic Winds (good for most use cases), VSL (dry and still nice sounding), Samplemodeling Winds (very realistic if you play it right)
-Brass: Symphonic Brass (large, British, mellow), Infinite Brass (Upfront, Action), Trailer Brass (Braams, Bold), Adventure Brass/Caspian (Action, Stacc-Marc lines, similar to Infinite Brass), Audiomodeling (or Samplemodeling, sorry) Brass (very realistic if you play it right)
- Choir: Oceania (great Stacc-Marc choir), Lacrimosa (on the bigger side), Dominus (soft churchy)
- Percussion: Spitfire percussion redux
- Piano: Emotional Piano (name speaks for itself), Keyscape (tons of pianos), NI pianos (Una cords is nice, grandeur is a versatile one), Fluffy Audio Scoring piano (I just like the sound), Olafur Arnalds Felt piano (nice felt, very soft and mellow), Spitfire Orchestral Grand (sits very well in an Orchestral mix, more oldschool "Goldsmith" sound, not good for "exposed solo piano"), Pianoteq
- Strings: Symphonic strings (big), Chamber strings (details, very nice sound, very nice articulations), CSS (more old-school sound, more feathery), Chris Hein Strings (nice Overall sound), Berlin strings (a favorite of some people)
- Solo strings: Spitfires solo strings, Sacconi Quartet, CSSS, Embertones Stuff, Chris Hein solo strings, Audiomodeling solo strings
- Other: Omnisphere of course, Komplete Ultimate, Super Audio Cart (video game sounds from consoles), and some small libs here and there like Spitfires Evos, Albions (4 and 5 are my loved ones). OT Ark series must be named as well here
Keep in mind - that's more my opinion. For a very versatile start you can also just get Komplete Ultimate+Omnisphere and do a lot of stuff, since you get instruments for pretty much every style, I closing the old VSL stuff, which in some cases still hold up very well (Harp, Woods). Plus you get Drums, Bass etcetc.
Don't forget a beefy machine to run everything on, a couple TB of space for the libraries and RAM to load everything in.
Dry vs wet libraries is a question that you need to look into - I use mainly wet stuff, that's because I like the sound of it. But when I do a different style, it bites me back a bit because some styles just don't go that well with a huge room like AIR. But for that I have other links to take that dry spot if I need it.
So in the end - a full must have imo is Komplete Ultimate and Omnisphere. You can do soo much with that already. Once you have some experience under your belt (don't know if you have some already), you can look detailed I to all libs and make good choices rather than spending 10k+ now to be able to compose every style. Chances are, I missed some other very good libs that are way better for some use cases.
