All U.S. airlines pretty much suck equally. Don't count on Delta being better than United/American etc. Emirates generally runs a lot smoother because they have more money than they know what to do with so they're adequately staffed and they invest more in their operation. Optimization and efficiency has been taken to the extreme with U.S. airlines in the name of saving a penny any where they can. The business model is "XX amount of complaints means we've cut things about right, XXX means we might have gone too far". Delta/United/American will have two check in agents working a 300 seat flight so they force you to use a kiosk instead of speaking to a person, flying with firearms you have to see an agent. If you try to get to an agent you have to wait in a 20 deep line. Emirates will have 15 agents working the same size flight and at any given time half of them will be available for you to walk up with no waiting.
For the most part you're always better off picking a foreign carrier over a U.S. carrier. The caveat with that is flying with guns, some like British Airways are openly hostile to firearms so you have to be careful flying them with firearms.
