I say the flying one.
If you can fly, which it turns out there is more air to fly in then there is water or lava to swim in, you can use your power more, which could save more money from not having to pay for any transportation if you have a push bike. But the huge con to that is that you need the bike, whenever you want to fly, and if you let go you fall..into your death. Its worth it though imo.
I dont have much water or lava where i live so..yeah