Based on the comments from others who've posted their AA experiences here, I'd say AA:
1. Apparently, based on the upgrade comments, they fly only 777-300ERs configured 100F, 12J, and 7Y.
2. EVERYONE is immediately granted their highest tier, after completing one flight.
3. They must operate flights hourly between any two points on their network.
4. As far as comfort goes, the consensus of AA cheerleaders is that AA Y is the equivalent of SQ J, AA J is the equivalent of CX F, and Emirates new F pales in comparison to AA's domestic F.


Seriously, I'd select an airline based on 1) convenience in getting you to/from your most frequent destinations and 2) FF programs.