I’m with the OP. Setting is the most important consideration for me. More than story, more than cool options, more than whatever character concept a player has been mulling around before they ever heard of this campaign. (I’m of a mind that any player can have a variety of characters they can enjoy playing, and they need to pick one that fits a setting and campaign, unless it’s an inherently shared DMing or shared campaign creation.) If a race doesn’t exist in a setting, the only way you can play it is if it came from another plane/world, and the only way you can do that is if a character coming from another plane/world fits the campaign. Both races and classes in my settings are fluff-integrated. You don’t pick a concept and then choose mechanics in the form of race/class combinations, and then fluff it however. A paladin, warlock, or even a rogue or fighter means something specific in the world. Some of these are broader than others and encompass a wider variety, like fighters that come in many different types. Others may be limited, such as all paladins of a specific subclass being members of the same knightly order, or cleric domains assigned to specific deities representing specific religious orders with unique roles in the world, or some races and cultural collections having a monopoly on some classes or subclasses. Setting first for me.