I went through a period of obsessively collecting whatever music software I could get my hands on, legit or otherwise. When I was pirating I told myself I was poor so I couldn't afford to make music legitimately (which is only a half-truth). Yes the best stuff is very expensive and still out of my reach (if I want to eat) but there's more than enough free stuff around to make a professional sounding track. Here's just 5 off the top of my head that I like and use, often in preference to paid software. This post is only really relevant to Steemit musicians who do in-the-box mixing. Not very interesting for others.
1. Acustica Audio Tan Compressor
Acustica are a small Italian company that invented the method for sampling audio hardware. It works a bit like an impulse response that you'd find in a reverb plugin. They pass a signal through a piece of hardware, then remove the signal, leaving them with a VST plugin that sounds 95% like the real thing.
Tan is actually my favourite software compressor, free or paid. I sounds a little like an LA2A, great on piano, guitar, bass and vocals.
2 Acustica Audio Red EQ
Another free hardware sampling offering from Acustica, Red is an EQ of three fixed bands. The bands are in a place which makes it sound great on acoustic guitars but it can be used for anything and still sound good.
3. Leeds Town Hall Organ from Samplephonics
Whether you're a classical composer or on a mission to bring back prog rock, this is an amazing 3gb+ sampling of a beautiful instrument. When I'm playing this on keyboard I get lost for hours. It works with Kontakt and a bunch of other midi samplers.
https://www.samplephonics.com/products/free/sampler-instruments/the-leeds-town-hall-organ
4. Audacity
Audacity started out pretty much like a virtual tape recorder and evolved into a fully functioning DAW (Digital Audio Workstation). I often prefer it to Cubase because it's very fast to boot up, so it's great if you've come up with something on guitar and want to record it quickly before you forget it.
It now has VST support, so you could download the two free Acustica VSTs and Audacity and have everything you need to make a professional sounding album (as long as you have a decent mic and some talent).
5. Purgatory Creek Rhodes Mark I
It appears the Kontakt version is no longer free (still only $15) but it's still free for Korg Kronos keyboards. It's one of the best Rhodes libraries out there with 18 velocity layers to prevent it from sounding artificial, also if you have decent converters you can reamp this through something like a Fender Blackface amp and it will sound amazing, indistinguishable from a real Rhodes.
http://shop.korg.com/Kronos/EXS-40
I realise this is a niche subject to blog about, but I will write more about tools for musicians if anyone's interested. So let me know in the comments if you found this useful.