tjbnwi said:
If they really want wood---Sherwin Williams Multi Purpose Primer, Duration or Emerald exterior top coat.
Do not use oil based paint or primer.
Oil based paint is still often used for demanding topside marine applications. In terms of performance, there is no reason not to use it. Some may have had a bad experience with it because it is too thick as it comes out of the can. Applied properly, it performs well especially where it will receive a lot of exposure and physical abuse like on railings, entry doors and railings.
I don't disagree with your Sherwin Williams recommendations.