Screw Sea Dogs and Raven's Cry (at least from what's been shown here so far)… the best pirate game money can buy at the moment is Assassin's Creed IV Black Flag
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OK, it's not exactly a RPG but in terms of nailing the 18th century Caribbean pirate setting, sea combat, exploration, upgrading the ship and plundering it's the pirate game I have always wanted ever since I first played Pirates! a couple decades ago or so. It's that awesome.
Raven's Cry would have to have super-awesome quests and characters (the ones in Black Flag aren't half bad actually from Kenway, the main character, to Captain Kidd and Blackbeard or non-lead roles like Stede Bonnet) to make up for its shortcomings in visuals, atmosphere or the sea combat etc.
Since I generally love the setting, I'm going to keep an eye on further opinions but it doesn't look like it can really hold a candle to Black Flag.