From my experience I've always preffered openGL. Partly because of it's heritage but mostly because of it's elegant design.
I dunno if you have ever tried to program using Direct3D but let me teel you it's unesseceraly difficult. Even getting a simple triangle on the screen can be difficult. In the end I gave up trying to learn D3D and moved to OpenGL, and boy am I glad I did. I had a simple Asteroids clone up and running within a few days, admitidly with the help of Glut.
I dunno if you have ever tried to program using Direct3D but let me teel you it's unesseceraly difficult. Even getting a simple triangle on the screen can be difficult. In the end I gave up trying to learn D3D and moved to OpenGL, and boy am I glad I did. I had a simple Asteroids clone up and running within a few days, admitidly with the help of Glut.