I don't know how much of your spend is on AA, but if it's very little, you might want to consider an SPG Amex business card. When transferred in 20k blocks, you get effectively 1.25 miles/dollar on SPG versus 1.05 miles/dollar on Citi Business, and (IIRC) the SPG annual fee is lower.

For the personal card, the annual 10% rebate alone makes the card worth holding.

In addition to all that, you might want to consider the following cards:
- Chase Marriott 70k. Not great for on-going spend for AA, but the signup bonus will get you 25k or so AA miles, and you get a free night every year.
- Barclays US Airways card. These miles will (probably) turn into AA miles sooner or later.
- Citi Executive AA card. High annual fee, but currently has a 60k bonus, and you can earn EQM if you care about that.

If anyone has other suggestions for cards with good signup bonuses that can be transferred to AA (without huge losses), I'd love to hear.