I like both places. I honestly think either would work. The thing to avoid is driving yourself crazy second guessing your decisions. I just came back from a trip where we arrived at WL, and ate our first dinner at the Contemporary after a long drive. We actually ate at the steakhouse, but we were seated RIGHT next to Chef Mickey's. It was fine. The boatride over was very enjoyable. After dinner, we took the monorail around to GF and walked around that resort, too. (Before dinner we hit the pool at WL, and explored our home resort some.)
The one thing you'd save out on is GETTING from AKL to the Contemporary. Sadly, ther is no direct boat from AKL tot he Contmporary. You can however, take the AKL bus to MK, and it's rather easy to walk over to the Contemporary. The only catch might be getting back - but only if you have a VERY late dinner and MK is closing more than an hour before your meal is to be finished, which isn't very likely.(You could still get a bus back if it's a Princess party night very easily.) And even then, the Disney staff would find a way for you to get back to AKL.
Dining at Boma, you wouldn't have to go anywhere, and it would give you a chance to explore the resort at night, which is very pretty. Boma doesn't have characters to contend with, but it's still a buffet, so you still have to make trips up to get your food.
We often find that we don't get to spend as much time at our resort as we would like to spend, so that would be a plus of staying put. On the other hand, after spending so much time in the car we were bursting to get out and move around and explore. If only one person is doing the driving, then that person will be tired. We traded driving and found that whenever we got somewhere we were all eager to move a little after being stuck in the car so long.
Finally, the last thing (or maybe the first thing?) to consider is that it night not be possible to get a seating at Boma at a time that you like.
It is fun, don't get me wrong, but not any place you want to be if you are tired.
