Add http://librocket.com/ to that list. I'm also wondering what is the best choice or the pro/cons of every library.

Pick the one that does what you need. Chances are, if it has tons of features and possibilites you'll never need you're just going to dislike the interface.

Do you need all the common fancy elements like sliders, radio buttons? Do you want your Gui to scale 1:1 with resolution (usually looks bad, but easy) or do you want to think in pixels? Do you prefer callbacks for events or a message queue for you to process? When you ask "what's the best something-something" you should rather ask "if there was a best one, why would the others still exist and be used" and then move on to "what are my requirements and what's the best one for that".

If all you want is a few buttons or maybe even just the usual "up/down/select/back" menu you can probably write one yourself in less time than it would take to evaluate existing libraries.

I use CEGUI and I'm pretty happy with it. Its got a good community, and I haven't had much trouble using it. I don't know the particular reasons why someone voted it as 'bad', but I just wanted to throw out a counter-opinion.

I'm using CEGUI, I've had a fair few problems with it but now I use it just fine. I would reccomend it but it may take a while to get fully to grips with it. I can't really say if its better or worse than others since its the only one I tried. It was quite simple to get the scripting working (lua).