While most people here would have you believe that Renaissance is the only version to ever get, Pirates of the European seas is also a worthwhile buy, if not at full price then during a sale. It improves upon many key points of the base game and fixes some of its bugs, though it does also introduce a few more. Some of the changes introduced in Renaissance change the gameplay in ways that aren't necessarily for everyone, and you might have more fun if you play Pirates instead. It goes on sale for 2 euro every other month, and at that price is very much worth it, even with Renaissance around. The only part of it that I'd recommend you avoid is the multiplayer, as that is hands down better in modded Renaissance.
