I have been testing various applications to see if I need a replacement for any of my primary tools. What are my primary tools? Well let's break this down shall we?
My primary tools for these jobs have recently been: Terminator for my terminal emulator. Vi and Kate for my text editor. Dolphin, PCManFM & nnn for my file managers. MusikCube and cmus for my music player. Evince for my pdf viewer. That being said I have switched to a few things for at least a month or longer now so my statements above are about the recent past.
I have been using plan9ports Acme and the Go port Edwood for awhile now. I was using Edwood but recently went back to Acme, as I got the same font going in Acme. The reason I was using Edwood was primarily for the sexy Kurinto font, that is no longer the case since I figure out how to use it in Acme! I have also stopped using KDE so Dolphin and Kate are gone. I have been using PCManFM for a while now and it's always been my go to light weight file manager. Let's go over each category and what I've picked.
I've found myself using a particular kind of terminal the past few years, having not really gotten used to tmux or screen, I've choosed the path of the self multiplexing terminal emulator. Terminator does just that, it allows for splitting the window into multiple terminal windows, it also allows for tabs too. So you can have tons and tons without the need for tmux. I don't save my sessions, so I don't really need the tmux features for this. What I also require is customizing colors and fonts of course. I do like that Terminator has a Mouse3 menu and a GUI for settings, this makes tweaking fast and handy. I tested a few other terminals, most of which did not allow window splitting like Terminator. I finally found what I was looking for in kitty https://sw.kovidgoyal.net/kitty/overview/ kiTTY is a great drop in replacement for a Terminator user like me, with one little caveat, it has a config file, not a GUI. Since switching to window managers again, I've gotten comfortable using configuration files again, so it's not been a bother really. Having to close out and reopen a new window for kitty each time you edit the settings is a little tiresome for the first few days as you set it up, but after that it's a set it and forget it config file. I actually like the look of kitty's tab styling and it has options for different ones if you don't like it. Check it out if you want, it's one of those GPU accelerated terminal emulators, so you do need some GL acceleration for it.
I have dived head into the plan 9 os / 9front world and started using Acme. I haven't used Sam much yet but I fell in love with Acme. It's mouse heavy, with mouse chording. So basically opposite of Vi is one way to think of it. There are videos online and it's been ported to most Un*xes. plan9port https://9fans.github.io/plan9port/ if you are looking for the right thing. If you can't find it for your platform and it supports Go, Edwood is a copy of Acme written in Go. It's supposed to be exactly the same more or less. The other editor I use is more of a preview / "Windows Notepad" type replacement. For that I've found xed https://github.com/linuxmint/xed It's written in C and simple dependencies. It's got more features than notepad but less features than Geany. So it's one of those middle ground text editors. Not Kate, Acme, Vi, or Emacs powerful. But Leafpad, Kate, and the like. It's a worthy addition to your toolset.
PCManFM, Ranger, & xfe. These are what I've latched onto. I recently discovered xfe, that is X File Explorer, as a lightweight full featured FM. The only thing I do not like about it is the lack of using my system icons, and using instead it's own sets of icons. PCManFM is my go to file manager. I've been using it for many years. It's a GUI FM that just works and is GTK. #1 FM for me. Now I also like Ranger as the TUI FM, it even supports images in the terminal if you use the right terminal, which I am with kitty.