I like the retro livery on the 757 which gives a more "metallic" feeling but the modern livery on the 787 gives a more modern feeling. Back to the physical appearances, the 757 looks special to me as it has a narrow body while having a long fuselage. I don't have any words to describe the 787 but just "fantastic!". Personally I feel that both are equally nice.
One way I will fly around the world!