I would have guessed that AA would select the new Rolls Royce Trent 787 engine.
http://finance.yahoo.com/news/AMR-Corporat...ml?x=0&.v=1
Regarding fleet renewal, American selected GE's GEnx-1B 74/75 engine for American's future 787 deliveries.
American also announced it has selected GE Aviation as the provider of engines for its expected order of Boeing 787-9 Dreamliners. American previously announced plans to acquire 42 787-9s with the right to acquire 58 additional 787s, which Boeing estimates are 20 percent more fuel efficient than the widebodies they would replace. In addition to supporting widebody replacement, the 787s are expected to support the growth American expects in the future from its planned Joint Business with British Airways and Iberia.
http://finance.yahoo.com/news/AMR-Corporat...ml?x=0&.v=1