If you don't care about points or credits, you can fly JetBlue from BOS-ORD. They're inexpensive, good legroom, complementary IFE, complementary snacks and drinks. I'm a fan. Boston is a JetBlue hub city, so flights from there are in good supply.
Whoever flys to/from the most convenient airports, at the cheapest price (presuming FF status/points etc arent factors). It's a short flight, doest really matter.
I'd be looking at Jetblue if not worried about SCs - they seem to have the best blend of reliability of schedule / price / "in flight experience" (for want of a better description).
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