Originally Posted by RevJim

Comfort is going to be about the same on all of those choices.

American Airlines is a Oneworld partner with BA, so you will at least earn miles with BA. American has a good priority boarding arrangement (separate lanes, so the gate lice don't crowd you out). They also have Fast Lane security at LAS.

On the down side, they have no lounge at LAS, and BA Bronze won't get you anything extra. I find at LAS lounge access is not really necessary because they have decent, free WiFi internet access throughout the airport anyway. There are outlets and charging stations around, so the only thing you are missing is a free drink and some snack mix.

AA is also based in the old D gates, not in the shiny new Terminal 3 (but who cares, the D gates work fine).

Because you specifically mentioned luggage as an issue I should point out I fly this route quite a bit with heavy luggage. My experience has been that the AA check in counter at LAS is very forgiving with overweight luggage. In AA domestic F you would normally get three bags at 50lbs each. I just flew that route with two 50lb bags and one 65lb bag, and they didn't care. Just put a heavy tag on it and checked me in. They checked my bags to my final destination (CEB, on CX) as well, so I didn't have to pay overweight charges for the international leg either. Obviously YMMV.

So I would recommend AA if you are carrying a lot of weight.