I for one am not a flight attendant....but lets think for a minute about what it entails to be a flight attendant. You have two purposes: safety and service. You have to always be punctual...can't be late and miss the plane. In the event of an emergency you must remain calm at all times and make sure that everyone evacuates the plane safely, restrain rowdy people, or tend to medical emergencies. You need to know how to operate all the equipment from entertainment devices, lights, doors, and the service carts. You also have to know the spiels that are said on every flight. Now with that in mind....you know you have to cover that and more in training.
Training varies per airline...but at the most strenuous it involves many weeks of memorizing various FAA regulations, airline lingo, and so on. College will help but I'm not exactly sure what courses...
Best airline?...well thats a pejorative call....depends on pay, coworkers, unions, and so on.
I'd suggest you just take a trip to the airport...and walk around...talk to flight attendants about their jobs as they get something eat before the next flight, or walk with them to the security checkpoints. Even better...get on a flight and talk with the attendents when they are all back at their galley posts and wouldn't mind sharing their opinions.
Last suggestion: watch Flight Attendant School (or something along those lines) which is a Travel Channel production that shows how one airline (Frontier) selects and trains their attendants...very stressful...but very fun and cool at the same time.
Good luck with your career search!