For the OP....
To what destinations are your 25-30 flights going to be? You can earn AA miles on these JetBlue flights listed here:
http://www.aa.com/i18n/AAdvantage/ea...es/jetBlue.jsp
Where do you want to go internationally? EU, Asia, South America, Africa, Australia? Europe/South America AA/one world is your best bet. Anywhere else: UA/CO.
Do you want to gain elite status and all its perks with a legacy carrier? 25-30 roundtrips will get you there pretty easily. You cannot earn elite points on JetBlue flights via AA however.
I personally prefer to fly JetBlue domestically from Boston but internationally Post-Merger UA/CO and Star Alliance may be your best bet for getting what you want. I'd get a OnePass frequent flier account and stick to CO/UA/US/AC/LH etc...
Also, I'd stick to a legacy carrier's credit card for earning miles. 65000 points can get you 1-2 relatively expensive flights to the Caribbean on JetBlue but 65000 OnePass miles is getting me a roundtrip from Boston to Bali with an option for a 2-day stopover in Bangkok, Stockholm, Oslo, Copenhagen, or Beijing.