I think I'll stick with British Air which has a direct flight from Phoenix to London; then I'll probably take a train ride up to Scotland.
BA used to be a top airline but they've lost a lot of their prestige in recent years since they abandoned most of their international direct flights from Scotland, including all their transatlantic services, surrendered many of their European routes to other operators, and stopped flying Concorde. In the past year or two they have had a lot of issues with the unions and a poor record for cancelling flights. Not an airline I'd choose to fly with, but each to their own.