I'd say having a similar world view helps a lot. That doesn't mean you have to agree on everything. I would agree with StellaInForest that having someone devoted to you and your relationship is probably more important, but having a similar worldview, interests, and tastes sure helps make things go smoother because there are fewer things you have to compromise on. Generally with compromise, neither party is fully content with the result.

You do need to know what principles are truly important to you. Those are more important to have in common than general preferences or interests.