I'll throw an x-factor into the mix and say it depends on the cut of the fish. If cut into steaks, I find the back sections to be really good. The backbone provides more of that goodness that only comes from cooking stuff bone-in. If filleted, I like a bite more or less from the middle of the fillet, just north of the belly, especially if pan seared. If I've got a big enough fish, I'll remove the membrane that covers the inside of the belly sections so the delicious, fatty flesh beneath can take on some of that delicate crunch from the sear. In that scenario, the belly is "king."