Gotta say Coke, though both are amazing. Pepsi has a less polarizing effect afterwards, but Coke has a better taste overall and I drink it more often (mostly because it's present in a lot of restaurants and all.)
Juice, especially orange or apple, very often contains more sugar that Coke, though. Also, what is terrible for your body is lack of exercise, not soda. If you keep your diet balanced and do sports, soda won't harm you.