First I’ll describe my approach and then I’ll give my recommendation, since my approach colors my recommendation. In my approach, I have 2 big libraries that I chiefly use and then a sprinkling of solo instruments and pads to fill in the details.
My main library is Spitfire BBCSO Core. I started out with the Discover version and loved it so much I quickly upgraded to Core. I really like the sound of the instruments and the sound of the room. I’ve had string passages I’ve recorded with it that sound just like strings from old film scores by Horner or Goldsmith.
My other main library is EastWest Hollywood Orchestra. This fills in a lot of the gaps that BBC has and I’m able to mix the two pretty well. In my template, most of my strings come from BBC. But I’ve found that BBC is not always great at doing fast runs on the strings, so I’ll use Hollywood for that.
Most of my brass comes from Hollywood. BBC has warmer, “prettier” brass but has trouble getting extra brassy when I need power, so I keep a few of the BBC articulations ready but mostly use brass from Hollywood.
For woodwinds I stick with BBC. I think their woodwinds are great and Hollywood’s woodwinds are mostly not.
For percussion I use a mix of BBC, another Spitfire library called Drumline, I think the cymbals in Hollywood are better so I use that for crashes and suspended cymbals. And I use another EastWest library called Stormdrum for big hits and more unusual percussion. And I have a collection of random taikos, toms, and homemade drums that I use.
I have a couple of solo instruments. Joshua Bell Violin is great. Tina Guo Cello too. There’s a bass clarinet from 8dio that I use often. And for pads, most of that comes from Spitfire LABS. They have a lot of versatile sounds and they’re free.
All of the stuff I just listed are there because I tried things, found things that didn’t work, and added more to fill that gap. For me, starting with BBC was great because it fits how I like to compose and it sounds like the style of music that I want to sound like. But I hit a limit with it when it came to brass and solo instruments. So I did the Composer Cloud subscription to add EastWest. For me the subscription totally made sense because I wanted to try it out and see if it fit my sound. I also knew that the EastWest libraries are older and starting to age out. And Composer Cloud includes a ton of variety. But Hollywood Orchestra did fill the gaps in BBC that I needed and let me write pieces with stronger brass and faster strings. But I still had a limit of solo instruments. I had things I wanted to write that required a violin and cello, so eventually I added in the solo libraries.
At this point I don’t feel like I’m limited by anything any more and I’m more in the tweaking stage. I think I’ll eventually drop EastWest in favor of something else. I’m looking at Cinesamples new Musio subscription platform to try them out. The main thing I’ll need to replace is the brass but I know that Cinebrass is supposed to be great. As long as Musio has that covered and maybe a few good drum libraries that will work. And I might get the library of solo instruments that Audio Imperia has to fill in some more solo potential.
So, I would not recommend Hollywood Orchestra by itself. I think it fills in gaps and mixes well with other libraries, but I think it would be tough to get any realism from only EastWest. I would recommend BBCSO, especially since you can try it out for cheap/free with the Discover version. You can even do some realistic things with just Discover. I think BBCSO is a great library that gives you most of what you need if you want more of an old-Hollywood sound. But you’re going to hit a limit with it where you’ll have to add things to fill the gaps.
I’m not sure if there is a true all-in-one library where you won’t run into a limit. I think BBC comes close. Albion One and Abby Road One are probably at a similar level. I don’t think Native Instruments has anything like that. I don’t know anything about the Red Room library you mentioned, but if it’s called a symphonic “sketchpad” then it’s probably designed for sketching and not full, fleshed out pieces. Metropolis Ark might work, but will depend on the sound you want, as it seems to have a more modern, harsher sound, which is great for trailers and hybrid scores, but less so for older style scores or moody atmospheres.
Longwinded, but now I’m done. Hope any of that is helpful.