There are actually three types of butter: salted, sweet and European. The question is which type is best for baking. It is a matter of opinion, but I am in the camp of sweet (unsalted) butter.
In order to meet the requirements of the USDA, all butter, salted or not, must have a butter fat content of at least 80%. However, there are no requirements for salt. Depending on the brand, sodium levels can come in as low of 600mg and on the high end 920mg. Salted butter also contains a higher percentage of water. So, it’s easy to see how salted butter could affect the finished product.
European butter is churned longer to achieve a butter fat content of at least 82%, has added cultures and is fermented. It can be found with or without salt, but for baking you would want the unsalted version. Overall, this style of butter has a silky, soft texture, a slight tangy taste, and melts faster than its American cousins. It is more expensive, but I think well worth the price for baked items whose flavor and texture depend heavily on butter; like Shortbread Cookies, Sables and Croissants.
Taste and test, as different brands have different flavors, and will have varying results. In the end, you will find what works the best for you.