I am looking at porting my game to use either SDL 2.0 or Allegro 5.1 and can't decide which to use, both seem to have great support for Windows, Mac, Linux, and both somewhat support iOS and Android. The 3D and shader API seems better in Allegro and when posting on the forums I always get a response from the Allegro community, while not one person has answered an SDL question. I thought more people use SDL though?

Does anyone have any experience with both libraries?

I am currently using allegro 5 and am very happy with it. I have indirectly used SDL via pygame. While It is really simple it cannot do most of thing youd want. And 3d with SDL is a big no no. Allegro has and will continue to have better support as it is very actively in development. Not so much with SDL. Although I cannot complain about the community support I got from the pygame community.

Thanks Lazerator, what platforms are you using Allegro on? Have you used multitouch with it?

SDL 2.0 is still active! It has come great ways since the old 1.2 version that was also used in pygame extension. If you are going 3D then you are probably going to be using OpenGL and SDL, SDL would just handle window creation and input or even Allegro and OpenGL together. Note SDL and Allegro 4.X and bellow are 2D graphics libraries, in Allegro 5.x up they seem to have added built in function but I read that their not that great, so you would probably end up using Allegro with OpenGL. I haven't used Allegro since a couple years back, was the first library I learnt for 2D games then we started using SDL and Ive been liking it since. I have SDL working on all platforms also with no problems, currently working on iOS app using SDL and OpenGL. Also note to get the latest SDL you need to download it from the Mercurial repository. SDL also has SDL_image, SDL_ttf, SDL_mixer, SDL_net library so you can add audio, text, load other image types, and networking, they all come separate. Also you say that no one has answered your SDL question? from the SDL website? I check in there almost every day and most questions get answered, sometimes it can take a day or two since many members work a full time job and help out with SDL on spare time.

I downloaded and tested SDL 2 with XCode 4.5 and it seems to be very much in development. Only half of the SDL tests compile and of those none actually run or do anything.

in Allegro 5.x up they seem to have added built in function but I read that their not that great, so you would probably end up using Allegro with OpenGL.

A5 does not have its own 3D routines, and this is by design. It directly interfaces with OpenGL (or DirectX) to allow 3D functionality if it is wanted.