It can do almost anything with the keyboard. I'd suggest just checking it out. A lot of people make changes to caps lock, shift key, left/right option/command, etc. I only do two things, setting fn to send hyper and swapping semicolon/colon. It's more about individual rules than a new keyboard layout (which is what Ukulele appeared to be in my 5 minutes with it).

Maybe other people can chime in on their uses, since I'm not the best to fully answer your question.

It also has a lot of prebaked configurations in it. For example there's one that changes Slovenian Apple layout (which is pretty nonsensical with @ on 3rd level) to the standard layout used by PCs. That's hugely useful for people who use Mac Minis / iMacs with non-Apple keyboards (since Apple refuses to add the standard layout to OS X).

With Karabiner that's an issue of a single tick.

Karabiner has support for most, if not all, keys on the keyboard. On a Mac, the Function keys aren't properly supported by the other key remapping apps. With Karabiner, I can use a PC keyboard to change screen brightness, volume, etc. I can also remap Fn+JKLI to the arrow keys, and much more.

Sticky keys are the big one for me. I have Ctrl mapped to act as Ctrl when pressed at the same time as another key, or to act as Esc when pressed alone.

It's not currently supported by Karabiner-Elements; I haven't found a way to do this on macOS Sierra yet.

This is what I am missing from Karabiner Elements. Did you find a workaround?

Keep an eye on the github issue; a few people have found kinda-sorta-workarounds. https://github.com/tekezo/Karabiner-Elements

I've postponed the Sierra upgrade on my main dev box until this is sorted out.

Seil does Caps Lock rebinding, I use it for keyboard layout switch.