I'm surprised that nobody has yet specifically mentioned the Tracker. For me, this is the single element that makes me so much happier to use Haiku that any version of Linux I've come across. (I'm currently using Mint, which seems a bit more user-friendly to me than other Linuxes.) I've been meaning to start a topic about the Tracker's uniqueness for a while, but it seems to fit this topic.
Every other OS has a "File Manager", which is a rather different beast. A File Manager instance can only view one folder at a time, so you are always navigating around and up and down. If you want to move or copy, you have to open another instance.
Tracker OTOH can have as many folders conveniently open as you like. And most importantly they are persistent! Close down your machine and you've lost all your File Manager instances. All your Tracker windows are still there when you reboot, so you can pick up where you left off.
I make good use of Workspaces, too. Typically I devote one Workspace to each topic I revisit frequently,. with all the relevant folders open there for quick access. For instance, I have a lot of music and midi files in various folders on my system, but one Workspace has them all sitting there for quick access when I feel like playing something. Similarly, all my photo and art-work folders are ready for me in another Workspace. I just counted, and I have 50 windows in 9 Workspaces...
Linux has Workspaces, too, but I seldom find them useful there. They're of slight use on my rPi, which runs 24/7; it's useful to have Terminals open on some of the processes, so I keep those in a 'non-work' Workspace, but on my Linux laptop, I never bother with them.
I suppose "in theory", Linux could have a Tracker, too, but I don't see it happening.