Earth. I'm a peaceful guy, am rarely near water, and the nice thing about earth that it is hard to defeat it. Fire is useless against stone, and water can't do too much. Ice would be a bit of an issue, but in my opinion, you can't defeat the sheer durability of earth and the ability to create stones and hurl them is perfect in a fight. Fire causes burn trauma and it takes a while to die from that. Water deaths usually are the result of drowning, which takes a minute or two. But a fist as hard a stone into your head is pretty much an automatic lights-out. Plus, try to shoot a stone with a bullet. I'm pretty sure the stone wins.
But, if I had the power of earth, I would honestly use it to help people. Crops grow, and since I live in prairie country, put some dang trees in. After that, I'd help out the cops by walking into dangerous hide outs. Like I said, rock wins over bullet.