all about apps
Quality-of-life desktop and cellphone aps that you can recommend to everyone?
I don't know if I can offer any for everyone, because the way I use computers and phones is not generally recommended: My current working OSes are Windows 7 and Android 9 (on a Galaxy Xcover 4) and neither has been updated in over a year. I don't update programs unless I have a problem and the release notes specifically say the update fixes the problem. The programs I mention could work differently or not work at all depending on what version your OS is on, and what version of the program is available. In some cases I've used oldversion.net to find working versions of windows software, or searched google for .apk packages of old versions of Android apps. Your mileage may vary, and for maximum security you should always keep your OS and apps up to date.
With that out of the way, here's the programs I get the most use out of.
I use Word and Excel 2003 (available on archive.org) for word processing and spreadsheets. For image editing I use Irfanview and paint.net. For text/code editing I use editplus (A very good program which should work on any version of Windows; I actually paid to register it.) For video editing I use avidemux and windows movie maker. For screen capture I use OBS. For web browsing I use Firefox ESR. For emulation I use bizhawk. For filesharing I use soulseek. For making and opening archive files, I use IZArc. For FTP I use winSCP. For music I use Winamp (and Foobar2000 for some plugins.) For other media I use VLC.
In general, my quality of life decreases whenever I use my phone, but I'll also mention the Android apps I've found that make the experience as painless as possible. In a couple cases I paid for the pro version, but I don't don't remember which ones and I don't know how to see what apps I bought on Android; none of them was more than a couple bucks when I bought it, but this may have changed. Some of these are only available on the F-droid repository.
For audio I use sicmu, antennapod and smart audiobook player. For reading I use ReadEra and KiwiX. I use a dictionary app called "English" which is really an offline wiktionary reader, but it works well. For video I use VLC. For notes and reminders I use google keep. My alarm app is an old version of "alarm clock plus" I found an apk for, I can't vouch for the newer versions. For internet I use kiwi browser, the wikipedia app, subway tooter, and flym (RSS reader).
Miscellaneous helpful apps: glimpse notifications (makes the screen turn on when I get notifications from specified apps, with recurring notifications); scoresheet (keep track of score in tabletop games); thing counter (it's like those handheld counters you click to increase the number by 1, when you need to keep track of things); ampwifi and "remote for VLC" (remote controls for winamp and VLC, require server plugins); CX file explorer (an actually functional file manager); and "just weather" (just a simple fast weather app.)
Good luck if you try any of these!