Vegeta. Vegeta became more powerful after the Piccolo fight against Frieza. Remember, Krillin almost killed Vegeta and healed him via Dende. Then we have that showing where Vegeta was able to see Frieza attacks and Piccolo wasn't. The only reason he was able to detect and react to Frieza attacks was due to the huge difference in power compared to the other Z fighters. With that said, Vegeta stomps.