Determining the sets a power should take by the shape of the AoE will always be a double standard, because either melee-range TAoEs will be taking ranged IO sets, or ranged cones will be taking melee IO sets (or you'll just be arbitrarily determining whether cones take PBAoE or TAoE, I guess, since apparently Range slottability doesn't matter). Determining it by the names of the sets, as in, semantically, is going to be extremely flimsy, and should basically mean every kind of AoE except ones that don't require a target would use TAoE sets.
Determining it by whether or not the power accepts Range enhancements is the only consistent, logical way to do it.