opengl or direct3D9 which one to use?

[Mugdog]

Ok, so experimenting with every game i have. I have came to the conclusion that the opengl settings seem to get me a better framerate. Now i see people all the time tell others to use direct3D9. Now im a bit of a loss here. I have updated dx9 and everything. I still seem to get a terrible framerate with direct3D9. I would like some help as to which one i should really use. My framerate in most games with opengl are 30-50(60 for ntsc). with direct3D9 im about 20-30 fps. Can someone help me as to which one i should choose? Give me a screen shot of which settings to use, etc etc please.