SFML is, hands down and even from an objective point of view, the best 2D+multimedia API out there and even if you want to do 3D it's probably choice #1 for handling sound, events, networking and the windows (unless you want to use DirectX of course). It's the fastest one, with the most features and the best/cleanest interface of them all. Not even mentioning the fact that Laurent is still working on it and will probably do so for the forseeable future, meaning it's not basically "dead" like SDL. Also there's barely any question that Laurent doesn't answer himself if you ask him.
I have no idea why there is even a single person who is still using SDL or Allegro with C++ and even more so, why people sometimes still suggest SDL or Allegro when a newcomer comes to a C++ forum and asks how to program games with C++. Both of those APIs are hopelessly outdated compared to this and SFML is soooooo much simpler and cleaner to use.
To be completely honest, if I was rich, I'd donate large sums to Laurent on a regular basis just because of the awesome work he does.
I've used Allegro Extensively, and SDL for quite a bit, but they just dont compare against SFML. They are definitely nice, but SFML easily takes the cake as my favorite, it took me all of one afternoon of playing around with the tutorials to realize this. 9 months later and im still happily using SFML for hobby and a LOT of school projects, both in 2d and 3d.
Here's my thanks Laurent, keep up the awesome work!