I'd like to mention that I've never heard of Polycode until just now. It says right on the website that it is in Alpha stage production which usually means it's not going to be ready for anything serious for another couple of years. SFML 1.6 is the current stable release and even though 2.0 is supposed to come out "soon" 1.6 is fine to practice with. SFML has a pretty large following and has actually pushed out SDL as the graphics library of choice for most users on this site.
Agreed... also, having to use multiple libraries for 3D graphics may seem intimidating... but SFML and OpenGL fit together like a hand in a glove. SFML will handle input, creating the window, sound, networking (and other things) while OpenGL will handle only the rendering.