Slept in coach on overnight flight. major pain in neck next day. would bucky or pillow be better next time?

It depends : In general, i would be hesitant to accept any advice that recommends a particular brand of pillow. What you should aim for is a pillow that provides enough support to be comfortable but which doesn't bend your neck too far. You should make a personal decision on what would allow you to rest comfortably on a flight. Focus on keeping your neck straight, and not bent, with your head comfortable.