First, buy from your local shop where you're a person not a number like at Walmart. Buying online can be done but after shipping costs and transfer fees might as well give the local guy the sale.
I also can't see buying a .270 or .30-06 having a 7mm but if one can justify it, so be it.

Myself, I'd go with whichever platform fit ME best. Find the gun that YOU prefer it's feel and hold of first. then decide onthe chambering. If your dealer has one in stock, buy that one. If your reloading, I'd proberly go .30-06 as it has more chocies for bullets.