I thinking that the massage might compared to one battle with the soothe bell,but I'm not sure.
Considering that battling gives no happiness, the answer is the massage. Its leveling up that increases happiness not battling. But leveling up gives between 2 to 6 happiness but the massage will give 3. But eithr way soothe bell will multiply everything by 1.5 so with the soothe bell leveling up will give you 3 to 9 depening on your Pokemons happiness and the massage will give 4 so depending on your Pokemons Happiness one would be better than the other but the massage is free so just do both. For more information look here: http://pokemondb.net/pokebase/118815/gen-v-happiness-quesstion