We've tried both and unanimously prefer 'Ohana (we've had 3 GREAT experiences there, though it seems to be hit-or-miss by what I read on this board). We didn't love Boma, but maybe it was just an "off" night for us, and we plan to try it again sometime in the future...when we eventually stay at AKL (in other words, we won't go out of our way again).
'Ohana has a lovely view of MK and sit-down service; There are no "choices" for food, but many things are served, so you would probably find something you like. There are activities to keep kids occupied, if that's a factor.
Boma is a buffet, so you have to serve yourself, but there are many different types of food to choose from.
AKL and the Poly are both worth exploring. Have you ever been to either resort? If not, choose by which resort you'd like to explore more...and you can see Wishes and EWP from the Poly beach after dinner! (Nice way to end a vacation).