I've used FAPA and Aero Crew, I think that Aero Crew did a much better job. FAPA was more mediocre.

Speaking of which, if you're going to AA, good luck. Last I heard, around 50% of their hiring is flow, 40% military, and 10% off the street. You're asking about interview prep so you're clearly not in the flow category, and if you're not military the odds of you getting a call from AA to interview are heavily stacked against you.