Which Format to Video: AVCHD or MP4?

I just purchased a Canon Vixia HF G30 camera. One of the reasons for doing this was video artifacts became apparent when viewing source material (and edited as well) from my old Sony HC9 on a new Samsung big screen TV. (I shoot underwater video, which by its very nature is light restricted. When shooting out in the blue, video banding became readily apparent) I also wanted "crisper" video that the new camera will provide. My question is which format is preferable AVCHD or MP4. I can shoot up to 28 mbps in AVCHD and 35 mbps in MP4. Since FCP X is optimizing the video to pro res 422 in either case, will the MP4 provide a better final product? (I end up making AVCHD blu-ray discs from the master quicktime movie at the end). Thanks.

Steve