Been using kitty for a while now, though honestly any terminal emulator works for me.

X11. It just works for me, no reason to switch. Plus I exclusively use Xfce or MATE which as far as I know do not have Wayland support.

The Caja file manager. Hell the MATE desktop environment in general is just perfect for me. Xfce is acceptable too, though the inclusion of CSD in recent Xfce releases has made me a bit more wary of it when it comes to theming.

I also use Waterfox as my browser. A Firefox fork that has the option to put tabs below address bar (where they belong imo) out of the box without needing to muck around with the userChrome.css file.

This exists, but it has the downside of being a web app rather than a native application. Can’t use it offline for instance.