Specifically I meant the pixel-blue window borders on i3, coupled with the extremely bare-bones status bar. (Does it even allow for systray icons? That would be rather important for me.)

Sway looks somewhat better, but I've been told it's still somewhat flaky.

Well i3 is kind of configurable:

http://dotshare.it/public/images/uploads/8435.png

http://dotshare.it/public/images/uploads/8284.png

http://dotshare.it/category/wms/i3/

>Does it even allow for systray icons?

Yes.

>extremely bare-bones status bar.

You can config everything in it, or use polybar.

>Sway looks somewhat better

Sway is a drop-in replacement.