The only times I prefer the 767 over the 777 are on BA, where Y is 2-3-2, and UA since F is 1-1-1 in instead of 1-2-1 and C is 2-2-2 instead of 2-4-2.
Love the 772 though overall! Best a/c on LY, best on overall on UA, and wonderful and reliable a/c.
(Also prefer the 744 for upper deck.)