Which is rendering platform is best to use with Beryl?

[Indigo 23]

I am running the latest nvidia drivers (from the ports -- 9746), Xorg
7.2, and Beryl 0.2.1.  I was wondering which is the best to use for
the "Rendering platform" option in Beryl.  I have the choice of 1)
Automatic, 2) Force Nvidia, 3) Force AIGLX and 4) Force XGL.  I am
wondering which would be the best to use? I noticed when I have it on
Automatic that I cannot run other OpenGL apps while Beryl is running
as it just forces me to kill X11 (the screen turns black and the
computer becomes very unresponsive).

Thanks.