I'm going to try to mention things I haven't seen already written, though I may repeat some of the more important ones to me.

(In no particular order)

Terminal:

• Kitty (Main Terminal)
• Fish (Terminal Prompt)
• Neovim (Code/Text editing)
• Zoxide (a directory changer; once you go to a directory, you can type z and a partial name to go back to it)
• Atuin (a command history lister, can get a key and bring over commands from other systems)
• Midnight Commander (CLI file manager)
• Btop (CLI system monitor)
• Palette (I do a lot of theming in different configs as well as HTML/CSS, so its nice to have something to quick convert hex to RGB).

GUI:

• Timeshift (backup/restore)
• Eddie (for AirVPN)
• novelWriter (my FAVORITE writing tool for my books)
• Floorp (Firefox fork browser)
• Conky Manager 2 (desktop monitoring widgets)
• Rofi (keyboard launcher)
• firewalld (tried this out recently, good firewall)
• Flameshot (ALWAYS; its my favorite screenshot tool)
• MPV (I still get VLC, but opt for MPV most of the time for videos/streaming)
• Speedcrunch (A+ calculator)
• Steam
• Lutris
• Protonup-QT (to inject GE Proton into Steam/Lutris)
• Stremio (a great little streaming tool)

I would like to add that I do use Arch, but I'm fairly sure 99% of these packages, if not all of them, are available for most other distros.

For CLI lovers: Check out Terminal Trove

Edit: I did see that someone mentioned no explanations on the apps, so I tried to put a little blurb on each.