Thunar is great especially if use Xfce or something like a window manager. One of the greatest features is adding the thunar-media-tags-plugin.
Caja is also great, it is the good old Nautilus when it still had all the features Gnome 3 removed, especially two panes hitting F3.
I too like Thunar, @vinylninja. It has built-in davfs2 support (for connecting to Nextcloud files, albeit it’s a bit tricky to initially set up), plus I think Thunar’s use gvfs is considerably faster when it comes to SMB file sharing, compared to KDE’s “KIO slaves” (~75% as fast as GVFS). At least, gvfs was considerably faster, last time I checked (in Feb. 2019).
Dolphin for me, too.
Although, I never had any issues using Thunar before I converted.
So I suppose the question is, are you fine with pulling in most of another desktop environment to get it’s file manager? Installing Dolphin to try it out would require me to add another 200MB-ish of KDE framework.
Now if you told me that a file manager allowed you to queue or pause file copy/move operations then I might be interested. That’s a feature that no file manager I’ve used does. It tries to do them all simultaneously and if you realise you need to use a drive for something but a huge move is happening you are kind of screwed for a simple way to pause that in a GUI file manager.
Nemo has the most complete functionality for me. I like Dolphin too, but I can never get it to play video files from SMB shares. From what I’ve read Dolphin doesn’t pass the password on to VLC for the share, only the username.
I’m a fan of Cinnamon and Plasma so either Nemo or Dolphin. They are similar in capabilities although I give Nemo the slight edge for admin capability.
For me it’s not so much thinking about pulling a file manager in to a different DE, but maybe switching DE’s based on the File Manager, as, to me, that is the single most important app that isn’t free standing (I can install important app X on pretty much any system, but the file manager is pretty ingrained in the DE)!
What does Nemo provide that Dolphin’s admin capability does not?
Specifically, open location as admin. KDE removed this capability.
For me it’s Thunar just for this capability and it’s default in Xfce. It’s easy to use, convenient and has the feature set I need.
(For anyone who wants ‘open as admin’ in Thunar and doesn’t have it, I don’t in 1.8.9)
Configure a custom action from the Edit menu, set command to be pkexec thunar %f and set appearance condition to be ‘directories’.
Maybe there’s a better way but I only just tried to do it.
It looks like Manjaro comes configured with the Root Actions service menu installed. You won’t see this on other distros to my knowledge. I believe these are seen as workarounds that are necessary because the KDE team removed this option from Dolphin due to security concerns.
Ah, I see. Well, I’m very new to KDE. I’ve been a die hard Xfce fan for the past decade. But even I can learn something every now and then.
Not that it matters, but I use the terminal more than anything else.
That is something Caja can do, too. It seems a lot of file managers can whereas Nautilus cannot but then I prefer to use the terminal to access files as root.
It could be removed by default in general because of security reasons already mentioned.
I tend to use the command line for editing single files but when I have to make changes to many files I prefer to use a root file manager session. In either case, it’s nice to have the choice.
Caja for me. It’s simple, efficient, and gets the job done. Thunar and Nemo are all right, too. I’ve never really liked Dolphin, but then I personally never seem to like Qt desktops.
And, of course, I quite often find myself using the command line to manage files, but that’s mostly when I’m doing web development stuff.
I like Midnight Commander. (mc). It’s a simple terminal file manager, that just works.
So, sudo pacman -S mc OR sudo apt install mc OR sudo dnf install mc, you get the idea. 
I used thunar for a long time when XFCE was my standard DE. I think I had a problem with it searching though, can’t remember, so used to use Dolphin instead for that. Apparently Dolphin is insanely powerful (not surprisingly, for KDE) but I’ve never really learned it. I think anything that’s a little trickier for file management might be better to do in terminal. Having said that, mostly I’m just moving files around, not much else, so the default in Gnome 3 (nautilus) suits me just fine and is what I normally use.
Hello,
My vote is D-All of the above, Just choose and use! 
