We've eaten at both, more recently Tusker House which was one of DH's favorites. We liked both but if you're doing AK park, TH is by far more convenient especially if you rely on WDW transporation.
But what I particularly enjoyed about going to BOMA's was getting to see the AKL & the savannah. But now that I've done that, unless I was staying at AKL, I'm just as happy to dine at TH on our AK day (lunch or dinner, have not done the character meal bfast).
I think both buffets were good & we had a good dining experience at both. Either one offers interesting choices IMO.