This post was written as a guide based on @LD-W's post on freeware for music composition. What is difference from his post is this one will go in-depth on my experience in composition with the free instruments, their functionalities and the good/bad about them. Also, hopefully I get sometime around to make guides like these into a series.
All of these tools and plugins I shared work across platforms. On Mac and Linux, these Win tools can run out-of-the-box with Wine without extra installation. All the DAWs I shared have native port for Mac. The best thing is these Win versions can also be installed on Linux/Mac via Wine if you preferred to work with the Win version.
A - DAW FROM NOTHING
Supposedly all you have is a computer, something really budget, like those really generic $300 laptop you got from Best Buy. You either have Win 10 or 8 pre-installed, or a Linux like Ubuntu.
The recommended DAW that I have worked with for years on multiple platforms are:
TRACKTION WAVEFORM (Win/Mac/Linux)
This is the closest thing to professional DAW can get for free on different platforms. Its UX/UI was designed after Ableton Live. I've used Waveform along with the discontinued free versions (Tracktion 7) for major projects.
FL STUDIO 20 FREE TRIAL (Win/Mac/Wine)
The flagship DAW for all levels from noobs to pros (by @EvilRaccoon). I haven't really bought FL 20 and still using the Trial/Demo version, because its trial features already fulfilled my needs for a powerful DAW for scoring.
There are two plugins by Blake Robinson that were developed to fix the missing features of FL Studio in film/game scoring: BRSO Articulate that to replace FL's MIDI Out for keyswitches in plugins like Kontakt Player, LABS or SINE player. BRSO Accumatime for replacement of Fruity Player to sync tempo change when scoring a video.
REAPER (Win/Mac/Linux)
Possibly the best shareware DAW out there that has complete functions even after evaluation ended. There is also a BRSO Accumatime version for Reaper.
ARDOUR (Win/Mac/Linux)
Can't include a budget guide post without FOSS. Ardour is possibly the most usable FOSS DAW so far, totally beats LMMS.
Why not other DAW? Problems I've encountered while working with other DAWs:
Cakewalk - Win only, doesn't work for Wine. Even if you have a decent PC, lagging and crash are main problems. The DAW's memory management was poorly developed and will spike when you have multiple instances of plugins opened. Hence the crashes.
Pro Tools First - Same as above. Also, incomplete and limited features. But what even more frustrating is the iLok protection that require you gotta be online all the time.
LMMS - Buggy as hell and incomplete features. Decent for beginners but after sometime you gotta move on.
Renoise - Free version is fairly limited, I don't recommend tracking for beginners.
ModPlug - Same as above. Features are KISS and handy but only if you are familiar with tracking.
SunVox - same as above. But using it for sound design is really cool.
B - YOUR ORCHESTRA PLUGINS
I'm gonna list the plugins based on its versatility and usability:
Spitfire BBCSO Discover
Orchestral library with good features for a complete orchestra setup. Lightweight and work out-of-the-box. Two-week wait time to get the lib. Here is an example I used it in latest track:
There is a small problem I encountered tho, when you load up multiple instances at once in FL there will be some hiss from CPU spike. I think they have fixed this in latest version of their plugin.
Spitfire LABS
If you are looking for deep-sampled intimate sounds, LABS have everything you need. My favorites from the library are Dulcimer and Frozen Strings. So far there haven't been problem with it. I used LABS in most of my composition.
Versilian Studios Chamber Orchestra CE 2
The best free orchestra for a long time before the other free stuff came along. Made by Newgrounders like @Troisnyx. Run on Sforzando
Orchestral Tools Layers and SINEFactory
Are you looking for full mic positions with your mixing? Layers is possibly the best free library that has almost full features of an AAA orchestral plugin. Dynamics, round-robins and the comprehensive mic positions. As its name said, Layers is for layering your instruments with other libraries. But it's also good for solo uses of basic composition. It's the only free lib that can go from soft to loud sounds with few tweaking.
SINEFactory includes three contents: String Ensemble with sustain and spiccato. Grand Piano, and 'Gearbox' which basically with 13 different percussion articulations. All three are on Full Mix, single mic.
ProjectSam The Free Orchestra
It's more like a series of Kontakt instruments rather than an orchestral lib. A lot of the patches came from older libraries like Symphobia and True Strike. What the benefit of TFO is you can jam it in a lot of big & wide sounds in trailer music, which is what ProjectSam libs are known for.
KeepForest Ferrum Free
Basically the ultimate free percussion library. I'm sad that Drumic'A was pulled but Ferrum replaced my needs.
Embertone Arcane
Quirky lib, but I really like the patch originated from Friedlander Violin.
Etherealwinds Harp II CE
By @Etherealwinds. Decent samples for solo instrument.
Keyzone Classic
Insanely well-sampled piano instrument.
Sonatina Symphonic Orchestra
The OG free orchestra library. This lib is over a decade old, way older than some of you. And it's still a decent one that can be used for small compositions and sketches. Run on Sforzando
Why not other libraries?
VSL Big Bang Orchestra requires USB dongle, which a bit stupid for a free library. Other than that stuff like
C - WHAT ABOUT THE HYBIRD STUFF
The stuff I use for hybrid compositions, aka a lot of wubs and brams:
Troisnyx
A better set of names to cite for VSCO2 are @camoshark, @Samulis, and @Jiimaan. I merely alpha tested it back in the day.