What Two Phone On What Two Carriers For Maximum U.S. Coverage

If you could get ANY two cell phones on ANY two carriers for maximum terrestrial coverage in the United States, what would they be? I would think I might be inclined to go with one Android and an iPhone. One would be Verizon and the other would be AT&T. I realize that a satellite phone would give better wilderness coverage, but I am referring simply to cell phones for this discussion. Anyway, would anybody here go with Sprint or T-Mobile? Or, would anybody go with a phone other than iPhone or Android?