I would either choose gravity or fire. I can repel to push them far away along with making them hit objects, attract to get closer to the enemy and cancel out their long range attacks or increase their gravity potential so they cant move and break their bones slowly. Isnt this Nagato's power?
This scene got me. To finally see Yang having a good time, laughing again even, and then when Taiyang said this and I was like "O.O WHAT" for a few horrified heartbeats and then she laughed and joked back and the relief was like a hot air balloon just rising up, just whew!