For a freebie, BBC Discover is excellent. One thing to keep in mind though @art1, the sounds are a3. This means 3 flutes, 3 oboes, 3 clarinets etc playing in unison. If you need solo instruments, I’m not sure if it will fit the bill. That said, it’s free, and it’s good sound for ensembles. Spitfire does top notch instruments, but they don’t come cheap.
I also have Halion Symphony Orchestra, which is good enough(ish) for my needs. This I had bought sometime ago during a sale for 50 euros, and it also has solo instruments too, not just ensembles. I also have London Strings of Big Fish audio which is around 100$, and is not bad at all for expressive solo strings. That’s a kontakt instrument.
Another option which has impressed me very much is Noteperformer. Noteperformer is outside the realm of Cubase, but it works with Finale, Sibelius (which I own) and Dorico. It really offers GREAT realism for the effort required, which is… none. You just write your score and noteperformer performs it. So that’s another one. If you don’t use any of these notation programs, just disregard this whole paragraph.
There are many VSTis that focus on the orchestra, exhaustingly so. The real question is what the use case is. Because while the level of control and quality (and price!) are undoubtedly high with Spitfire, VSL and the likes, so is the level of effort required. (that is, managing complex expression maps, micromanaging CCs, articulations, and mixing those together to achieve a realistic performance).
That said, I do not know if those instruments allow for the level of control you envision. A marcato sample of the first desk of the 2nd violins is just that, I don’t think you get a “synth-like” control over the attack or such. I might be wrong though, as I said I don’t own any of the “big guns”.