Hmm ... good question. Based on my own observation, I would like to give credits to these Charges of Theta Delta Chi:
Kappa Charge (Tufts) for its longest continuos existance, since 1856
Zeta (Brown) and Omicron Deut (Dartmouth) for their large number (yes, Ivy League school! Who-oo)
Eta Deut (Stanford) for its large number, even though the school environment is no longer Greek friendly anymore (hang on there buddy)
Nu (Virginia) for its beautiful and historic location