Okay....I was torn too on the last trip....so I wound up doing both. And, again doing both again this year. I am not a picky eater, but then again, I'm a picky eater...make sense? How about this, I'll try it once if it looks visually appealing, but after that one time, that's it if I don't like it. Anyway, back to what I'd say. They both have their pros and cons.
Boma: Pro.....Buffet...many different choices....childrens section if after all the food you try you don't like, you can go for that pod.....the desserts (wow

). Con....buffet....many choices....childrens section if you don't like anything.
O'hana's....Pro....Family Buffett (you don't have to get up) The lazy susan in the middle of the table's wonderful food.....meat on a skewer, brought to you hot and ready to eat....great view of the castle....wonderful atmosphere....
Con....The lazy susan in the middle of the table's food gets cold....meat on the skewer can be dry sometimes.....if you are not into watching kids games, or don't have children and don't want to be bothered with them, make sure they sit you far off the beaten path. (Please don't flame me, but it was just DBF and myself, and they put us near the walkway. I like children, he has a daughter and likes children, but we did not enjoy children leading coconuts around the room with broom sticks and the coconuts found their way under the table and we got a few good whacks on our legs for those trying to get their coconuts. The CM did apologize after they passed and asked which one was ours. The look on her face when we said we didn't have any, she apologized again, and thanked us for being good sports).
Now, my BF is an adventurous eater. He loves Boma's and he LUV's Ohana's (huge shrimp fan). I told him to pick one, and he pitched a fit. Why couldn't we have both...blah blah blah....(there for a minute I realized I do have a child..

) So we are doing both. I'm not going to pick one over the other for you. Where I might have a fantastic time...you might have a poopy time. where I might have a poopy time.....you will have a fantastic time. Go with your gut....do you want poly atmosphere or African atmosphere? Do you want many many choices, or 5 appertifs, 3 sauces, 4 meats, and a carmel dessert (if they still do that!). No matter where you choose, enjoy it, your at WDW!!!!
I'm long winded I know......
Have a great time! Let us know what you pick!!!
Chris