UA post 3/3/12 has been a complete joke. They lead in overall mx and cx nowadays, while FA's and the rest of the employee base have lost "interest" in the brand and customer service... it shows, quite sorely. Jeff Smisek ruined a great brand, despite the "changes you're going to like" line he gleefully explains in the intro video onboard.

I used to be a CO guy. Loved that airline, but news of the merger in 2010 made me rethink it and move to DL. Kellner went off, and Smisek took over, leading the merged UA in a nosedive. Stay away at all costs. I'm sure you enjoy DM now, on UA think 1k CPU's going to "FCM", non existent customer service, multiple weather and mechanical delays,... just the tip of the iceberg.

I've heard great things about AA but am hesitant to build a mileage bank there with potential merger rumors. The route network is not as strong as *A, but OW is ok. Stay on DL, and like others have said, try to get "lifetime DM"