What paint or stain would you use for a wood deck top railing that f

Sadly, nothing is safe from the sun forever. Valspar products are meant to be used on boats, and are going to resist sun about as long as anything will. If you can't get Valspar, read labels for a product with UV protection.

I have quite a large deck with a railing and spindles that was installed on the south side of our house in 1994. I did the original priming and painting before installation. Trust me I have painted and touched up the spindles many times. All 68 of them! That doesn't take into account the lower deck and railing. If this is not new wood the most important thing to remember is to clean your railing really good before you paint . For years now I have used Valspar exterior satin. I like the sheen it gives. New wood make sure and use a good primer and GOOD paint. I think that is what has made mine last over the years is I do not scrimp on the paint quality.