To answer OP's question....

What sort of annual CC spend can you commit to and what is your end goal in terms of AA status?
That will tailor your plan....

If $40K annual CC spend is do-able for you, the Citi Exec card presents a compelling option:

• Works well to compliment your regular AA travel w/ an Admirals Club membership
• Earn 1 LP per $ on purchases
• "Bonus" LP's for the spending goal of $40K.
• Other card benefits might be useful?

Others laid out good plans for $40K spend on AA Exec only to start, and then add'l spend on Aviator Silver (if you have that card) for incremental spending bonuses up to a grand total of $90K spend to acquire 25K "bonus" LP's.
See post #3 : https://www.flyertalk.com/forum/33856034-post3.html

If that sort of annual spending is not in your wheelhouse, and you are looking to use CC spend to supplement your butt-in-seat LP earning on AA flights (and you don't have a need for an AC membership).... I would suggest the AA Plat card.
You would still earn 1LP/$ on your purchases, you earn 2RDM/$ on gas + restaurants (still just 1LP/$ on that category), and with just $20K spend in a year you get a $125 coupon for AA flights. And at $95 AF, its not a budget breaker to be in your wallet.

For me, I can hit $90K spend between the 2 premium AA cards to hit the bonus and then some- likely PPro territory on CC spend alone, maybe to EXP with some actual flying which has been limited as of late for obvious reasons.