I'm a big believer in high-quality gear. There are two brands I wanted to post here because I think they're great for sailors.
First is Smartwool. They are run by VFC which is NYSE: VFC they are a big company (over $12b in revenue) and have a number of sports brands. The Smartwool stuff, from the socks to the long underwear, is simply amazing. Warmer than ploy when wet and doesn't stink. If you haven't worn Smartwool under your foulies, you really owe it to yourself.
Second is American Giant. They are a local company (SF HQ) and manufacture everything in the US using US manufactured fabrics. Their stuff is all cotton (almost) and once you put one of their sweatshirts or work shirts on you will never buy a different brand. In climates where it's too warm for wool, I think these guys make the best there is.