Its really a question of preference. a good blueing is going to look better to a blue/wood kind of guy. It seems that Rugers often don't blue the cast receiver very well, so I would ask the smith doing blueing that he can make a uniform finish on both barrel and receiver.
Cerakote can provide a very weather resistant finish (although it won't protect the bore) and can look good, but its not as traditional as a good blue. Its pretty tough, but its not forever, you can chip and or wear it away.
BTW don't be worried about sending out a barreled action to a smith, Its not that hard and might add $50 to the price.
Short of a saltwater environment, you can keep either a blue or cerkote rifle from rusting.
