Would say the GT-640. Some 72 kh/s with scrypt, but still some 1.45 kh/s with keccak. While a 780 Ti (this is now only a guess from reading past posts!) manages around 700 kh/s scrypt and around 4-5 kh/s keccak.

[Edit]
Or do I currently mix up keccak with an other algorithm?