Obviously, I don't like Windows, so this is kind of like a last resort option if you must use Windows. Windows is bloated, insecure, not privacy-friendly, and just in general a horrible operating system to use. But if you must use Windows, at least these programs can lessen your reliance on proprietary garbage.
Web Browser: Firefox (or any open source browser)
For most of us, the program that we use the most often on our computers is going to be the web browser, and sadly the web browser market is dominated by insecure and proprietary options such as Google Chrome and Microsoft Edge. Just by changing your web browser to an open source solution such as Firefox, Brave, or Chromium, you're making a substantial step towards software freedom, and after a few days of using it you're not even going to notice a difference.
Firefox has loads of addons available, just like Chrome does, and has the added benefit of extreme customizability, meaning better control over your privacy and security depending on your threat level.
Email Client: Thunderbird
If you use an email client such as Outlook (which isn't even that good of a software), I highly recommend changing to Thunderbird. Made by the same people that made Firefox, Thunderbird has stood the test of time and it's always easy to get started with its intuitive interface with no fuss.
Boasting increased privacy settings and support for encryption technologies such as PGP keys, Thunderbird is in every way one of the best email clients around, and will run laps around Outlook.
Office Suite: LibreOffice
Literal God Tier software right here. Used by millions, LibreOffice is the definition of amazing open source software that is on par with every major office suite out there. There isn't a single simple thing that the Microsoft Office Suite can do that the LibreOffice Suite can't, and if you're not a die hard Microsoft Office Suite user that needs very specific functions, then LibreOffice will 100% satisfy your needs. I use LibreOffice on an almost daily basis, and I've never had a major problem that a quick web search didn't fix.
Ditch Windows Media Player and whatever the default media player is in Windows 10, and just get VLC. There's a reason why VLC is so widely used by people, because like LibreOffice, VLC is proof that open source software can be amazing software that can actually surpass their proprietary counterparts. VLC is software that "just-works" with no hassle, just set it as your default media player, and enjoy high quality videos with peace of mind.
Personally because I run GNU/Linux, I actually prefer to use mpv, which has better support on Linux, but apparently mpv.net is a version that works well on Windows, so it might be worth checking out.
Archiving Software: 7-Zip
I don't know why people literally pay for archiving software like WinRAR. WinRAR is proprietary software that has lower compression ratio than 7-Zip does, so there's literally no reason to use WinRAR. Just use the open source 7-Zip, and enjoy superior compression ratios; 7-Zip also supports RAR, ZIP, and many other archives too if you need to create or extract them.
Video Recording/Streaming: OBS
Open Broadcasting Software (OBS) is actually already used by the majority of streamers and people who need to record their screens, so if you're one of those people you're probably already using OBS; if you're not, what the hell is wrong with you? Literally everyone is using OBS for streaming and recording, and for good reason, so ditch whatever the heck you're using and switch to OBS.
Seamless integration with Twitch and every other major streaming platform, amazing GUI for setting up complicated scenes and transitions, simple and advanced settings to tweak OBS to your liking, OBS is everything you need to get started with your streaming and recording needs.
I'm not a video editor, and I don't do it very often, but when I do, Kdenlive is enough for my simple editing needs; I'm not going to say that Kdenlive will fulfill your complicated needs that proprietary solutions such as Adobe Premiere offers, but it should be fine for simple editing and transitions. Like all video editing software, they all have a learning curve, so you might have to play around with Kdenlive for a bit.
Audacity I'm pretty sure is already used by a lot of people that needs to edit audio or record audio. I haven't used Audacity much, but when I did it was simple enough to just start recording and not have to worry about it.
I've been using GIMP for quite some time now, and I don't do much complicated editing, so GIMP works wonders for me and was a fine replacement for Photoshop. Obviously this will depend on your use case and whether using Photoshop is mission-critical or not.
Inkscape is a software for drawing and editing scalable vector images, so if you need to do that kind of thing Inkscape will suit your needs, and I hear that Inkscape is already the best software used by many people that work with vectors.
That exhausts the list of software that I deem essential replacements for the proprietary garbage that is on most people's systems. By using all of these pieces of software that I listed here, you're drastically loosening the grips of proprietary software, and also preparing yourself for when you want to move to a free and open source operating system such as Linux.