Neither they both start out weak and lock you to that move which greatly hinders their usefulness. Go with Avalanche or Stone-edge if you want an Ice or Rock type move. You should go with Avalanche because it strong against Grass types which are the only weakness of Swampert. A good moveset would be Waterfall, Earthquake, Avalanche, Curse.
Note: Just in case you did not know Avalanche doubles in power if you move last, so it goes from 60 base power to 120 base power and because Swampert is slow he will frequently move last.