I've not yet tried GLUT but SFML is a good library, used with C++, cross-platform and glut can even be used on SFML. I also has a network package, and supports multi-threading.
Maybe googling SFMLvs GLUT might give you some results.
GLUT is a wrapper for OpenGL. SFML is a wrapper for a window manager and can create your OpenGL canvas, you still need to OpenGL (of course it can do other things too). Since the OpenGL part isn't done by SFML, you can still use GLUT at the same time instead of writing directly with OpenGL.
Therefore use SFML for your window manager and/or 2d graphics. Use GLUT for the OpenGL wrapping. They are not exclusive libraries.
I thought GLUT was a window manager? And wrapped things like texture loading (which SFML also does).
(Likely not comprehensive) feature list from the GLUT webpage:
Multiple windows for OpenGL rendering
Callback driven event processing
Sophisticated input devices
An 'idle' routine and timers
A simple, cascading pop-up menu facility
Utility routines to generate various solid and wire frame objects
Support for bitmap and stroke fonts
Miscellaneous window management functions
SFML does most of that, but granted not all of it.