scene2d.ui is what I was planning on using. I just didn't know if there was anything better. I'm finding a lot of old documentation and having some problems getting it going.
Another concern I have with scene2d.ui is I don't think it has anyway to do a tabbed screen.
Better is a matter of opinion. I'm not really a libgdx user, but I would say that if scene2d.ui can handle what you need, then go with it. Since it's already a part of libgdx, you won't have to worry about any potential compatibility quirks with the rest of the library. There are plenty of alternatives
, but if you're wanting to develop for/port your application to mobile, you'll have to do some digging to see how suitable they are.
As for tabbed screens, it shouldn't be hard to roll your own using the available widgets. Conceptually a tabbed control is nothing more than a split pane with buttons in one half that set the state for what should be displayed in the other half. If you have to make your tabs "wrap", you may have to put a little more effort into it, but overall it shouldn't be too complex one way or the other.