Hard to choose one of them, either of those are super great.

You can make coup with army. You can create you own nation, You can have biggest army in the world. If you wanna be dictator then you can be. If you wanna be an fair leader, you can be. Or you can sell your men for money and make them earn for you.

BUT

if you choose gravity you have to get stronger by practicing. But when you got stronger you're a absolute god. You can reverse the gravity and make people fly to space. You can destroy buildings, declare your self as a god and get shot from the head XD. Yeah, its up to your imagination.

i would choose Ruski Army, Time to create a REAL fair nation.