I have never used dwm seriously, but as far as I can tell the main feature it offers over i3 is tagging. I don't really understand how this meaningfully changes the day to day workflow, and I'd love to hear what you consider to be the advantages.
Personally I prefer being able to quickly toggle a dynamic window layout based on my current workflow, and switch back to manual tiling when I specifically need to manually tile.
Currently I use Sway too as it's the most mature tiling compositor on Wayland, but once River WM[0], also based on wlroots, matures more I think I will likely make the switch because I often miss dynamic tiling.
[0] https://github.com/riverwm/river
On a side note, I hate how window moving works in Sway/i3. I can hardly ever get windows to move to where I want them to go with keyboard. As a result, I have a bind that enters a 'move' mode that takes the current selected window and moves it to a window that I can select. That, or I just use the mouse to drag the window, which is kinda annoying considering this is a keeb focussed environment.
What are you specifically referring to when you say "tagging"?
That's because this feature is not a Freedesktop standard. The X11 root window have a property _NET_NUMBER_OF_DESKTOPS and a few more[0] to help implement this behavior.
Most tiling WMs choose to ignore this standard in favor of this great feature. But the WMs of Gnome, Xfce, KDE, etc... will probably never implement it just in case some apps don't support it (like some games that needs to be floating windows in tiling WMs).
[0] - https://specifications.freedesktop.org/wm-spec/1.3/ar01s03.htmlhttps://www.freedesktop.org/wiki/Specifications/
> freedesktop.org produces specifications for interoperability, but we are not an official standards body. There is no requirement for projects to implement all of these specifications, nor certification.
Freedesktop doesn't have any sort of authority, while it does provide some useful specs (e.g. the .desktop files are in general useful), not everything they do is like that.
The reason that this isn't found in floating WMs is simply that the developers of those WMs didn't found it useful to implement it, not because of Freedesktop (which BTW could update EWMH to include such a thing, it isn't like it has to be written in stone).
OS X has the same issue as a lot of other VMs. You can not simply have a single pool of workspaces and chose to view any N of them, where N is the number of monitors that you have. In OS X you can have workspaces on your left monitor, and workspaces on your right monitor, but you can't easily share the workspaces between the monitors without re-arranging them.
The only WM I have used that gets virtual desktops right for multi monitors is xmonad. Maybe dwm can work the same way, not sure.
In xmonad you can have 10 workspaces and 2 monitors, and pull up any workspace on any monitor. You can have hotkeys to cycle workspaces on either monitor independently and a key to swap the two monitors.
Even now, they still don't get it right and treat each monitor as its own set of desktops.
Now, if macOS could get auto-tiling options like Linux has...
If you decide that you want to see two workspaces from your center monitor, can you easily pull up one of them on the right monitor? The only thing I've ever used that lets you do this is xmonad (described in another comment below).
For me, the killer feature (aside from tiling vs overlapping) is that on my three monitors, I can switch virtual desktops independently on each monitor. After being able to do this, I don't understand why every window manager doesn't offer this. It's not uncommon with tiling WMs that have good multi-monitor support, but you really can't find it in traditional WMs. There's an unmaintained patch of openbox--openbox-multihead--that added the feature, and there's an "experimental" hybrid window manager written in Go (by the same author of the openbox patch), but no mainstream window managers appear to have the feature. Apparently it goes against a requirement/assumption in the EWMH spec and breaks existing pagers. But that's okay, because I don't use a pager.
Anyway, it really is critical to how I work now. I can keep a set of windows on my right monitor, and flip between virtual desktops on my center monitor without the right monitor changing at all. (And no, using the "sticky" feature of other WMs doesn't work for me because sometimes I do want to flip to a different virtual desktop on the right monitor and have that set of windows for whatever context I'm switching to). Along the same lines, the pertag patch is part of making dwm the perfect windows manager for me.
(If you're interested in the particular set of patches I use and my config, I maintain it at https://github.com/racingmars/dwm)