PNMsMOM good luck with rush! It is great you are helping your daughter with gathering information. It is a stressful time, and having the support of your family really makes the difference.
OSU has a great greek system. A lot of my friends from high school went to Ok State. My best friend was in the Gamma Phi Beta house up there. And her sister was a Theta. Both great houses! But I think they are one of the lucky schools with all strong groups. At least a few years back that was true.
Also check the mandated residency for each house. Some girls really don't mind being required to live at the house for three years. But some want the absolute minimum. I think most of their groups require two or three years residency. Might make a difference.
Wish we had Alpha Gams at OSU. But we have great chapters at OU and UCO!
Good Luck Again!!