Sikkens marine varnish
The really hard finishes are the most work to maintain. The little bit of flex in Cetol allows to give and take thus hold up longer.
If you want that deep polished glass look (many folks do) then you''ll need to work your butt off to keep it. You''ll want a full canvas awning to keep the boat covered any time not out on the water. I''ve seen them look that good but I sure wouldn''t want to own one<g>.
Cetol may not be the look everyone wants but with a small amount of work it will stay looking good.
You can use other products on the interior as it won''t get the sun and salt spray that the outside will.