No hash function is perfect, but some are useful.
wyhash and wyrand are the ideal 64-bit hash function and PRNG respectively:
solid: wyhash passed SMHasher, wyrand passed BigCrush, practrand.
portable: 64-bit/32-bit system, big/little endian.
fastest: Efficient on 64-bit machines, especially for short keys.
simplest: In the sense of code size.