Finally answering my own question...
I would choose Tri Delta. I've already indoctrinated my daughter enough by (almost) age 4 that she'll be a Spartan to some degree no matter where she ends up going to college.
But there are no women in any of my extended family on either side who are Greek and I would love to share Tri Delta with her. If not Tri Delta, just sharing the Greek experience would also be rewarding.