Pidgin. Consume soo little memory in comparison to other chat applications. Is really fast, just try start and scroll history in a chat conversation. But it looks ugly.

Hey what about Kodi?

I use Gimp and Krita, ShareX also with the complementary Extension, integrated with FileCoffee, old but gold VLC media player, PicView image viewer/editor (IMO best alternative to IrfanView), ProtonVPN (yes, it's OpenSource), Crow Translate, FreeTube, Portmaster, Cherry Tree editor, apart of some games (The Dark Mod, Armagetron Advanced, Scorched 3D, and some more)

Are we allowed FOSS alternatives to common FOSS apps lol? In which case, I'm saying NeoStore > F-Droid.

Also, separately, Zotero > all commercial reference manages and increasingly over PDF readers too.

I don't 100% understand LPPL, but I believe it qualifies under open source, but regardless if it's open source or not, LaTeX > Word and I will die on this hill.

Godbolt. Thank whatever cosmic great fortune sent goldbolt.

1. XBMC forked off into Plex. Plex introduced a far better UI.
2. XBMC became Kodi. Kodi learned from Plex.
3. Jellyfin came along and learned from both of them.

So I don't think you can really criticise Plex too much here. They were perhaps getting complacent and they've definitely been shown up, but they were an important step to where we are now.