... I haven’t found one that works well with dialog, fixed sized, or modal windows well enough to not get annoying,

This so, so much. I:ve been on Sway (and i3 before) for a long time and this is such a pain in the ass.

Most gui programs that do more than a simple window just don't work well with them, dialogs filling up half your screen because of tiling, programs with detachable panels that turn into windows cannot be attached again because the main window doesn't detect it (puddletag is an example I've came across recently).

I know I can setup some rules to make the windows float or have the correct behavior, but it's just too much to fix every single broken dialog I encounter.

That's kinda why I'm waiting for COSMIC to mature more. Based on what I'm doing I sometimes prefer floating, sometimes floating. So a DE where both modes are supported equally and can be mixed and matched would be perfect for my preferences.

while most traditional window managers/desktop environments have good enough keyboard shortcuts and window snapping.

The secret that the tiling wm people don't want you to know: with a little effort of configuring settings and setting up/learning some keyboard shortcuts, KDE can behave an awful lot like a tiling wm when you want it to ... while also still behaving like a normal DE when you want it to.

currently trying to use sway and I am finding out just how much I miss being able to alt tab through windows on a monitor