Poly Planer. They last forever. I had some on my offshore center console for almost 10 years. No issue. Same with their radio's.
I have them on my Chris Craft also. Water spray does not bother them. Neither does salt spray.
They are not high end, but last longer than anything I ever tried.
I have tried Sony and Jensen marine radios/speakers with not much luck.

Ive got kenwood on my rhino pro-box and have sprayed it with a good amount of pressure to clean the mud off and ive had "0" problems with them and very satisfied with the sound quality

Infinty Marine sound great and so do the JBL's. Best on the market is the JL Seperates but you will pay for them

I was wrong I just got in the boat to plug in my charger I've got the Infinity Marine speakers. The ones with the directional tweeters.

Fusion marine speakers and amp in my boat they sound pretty good dont know how much they cost.

Poly Planer
 

By far the best I have seen. They sound great and handle the salt with no problem.

The only draw back is the $$$$$ but I think they are well worth it.