The 3 best eels for the reef in no particular order:
Zebra
snowflake
chain link

They are all good choices. Zebras are a bit clumsy and large though, so i would still keep one out of a reef with corals that fall over. Cant go wrong with the snowflake. Moderate size and tends to poke its head out towards the front of the tank. The chain links are small and very pretty, but I hear they can be really, really shy. I say go with the snowflake for a 60. If you cant stand to keep something that is common, the chain link is an option.