Wait, really?

I did not get that impression at all when I was looking at it…

(I'm looking at it again now though and their dev guide/API is nice and has nice explanations which makes me happy)

Wow, that looks really impressive! It seems to have anything GM has and more :D. I'm not sure if it does handle everything as easily as GM, but it is certainly a valuable tool none the less. The only annoying this about it is that its a library for Java. I messed around with java a little and I really dislike the language :(. It could be that i'm not used to the proper object orientedness of the language, but i just find it difficult to read and maintain.

If it was a library for delphi i would be happy, that language is so awesome and its fun to write in lol, pity its a more or less dead language :(. Really good tool though, and if I ever want to move off gamemaker, and feel like living with Java, I think this looks like a really API. :D

Having used both, they take about the same amount of time to get up and running. In SFML you spend a little longer with initial setup (if you are compiling it yourself), but once you do it's trivial getting a sprite on the screen (load texture into sprite; draw sprite). LibGDX is ready to go out of the box thanks to the simplicity of java libraries. It takes a little more time getting familiar with the conventions of asset management (how to actually load resources and from where) and batching techniques.

Though either way you still have the rest of the library to learn as you go. SFML API is a bit more lightweight (meaning more emphasis on how you structure things yourself, but it's quick to become familiar with it all). In LibGDX there are usually a couple ways of doing most things, and which one you choose is largely dependent on your application. LibGDX has more auxiliary classes that do a bit of heavy lifting for you, such as rendering tile maps (supports loading TilEd maps), basic collisions, and also out of the box physics support (Box2D). With SFML, it's up to you to do these yourself or get another library for them.

Really it just boils down to preference. They're both capable of the same things in the grand scheme of things, and really what's more important is how you structure your code to make your actual game. SO if you like Java and hate C++ or using bindings (SFML is available for Java), you'll probably be suited with LibGDX. If you hate Java and love native C++ libraries or using <insert favorite language here> bindings, then you'll probably feel most comfortable with SFML. Just go make your damn game already!