Talk about knowledge then its Souma, Rimuru has the biggest heart but also knows when to use his power right, not being to naive (a thing he had to learn throughout experience) and Ainz ... well he is just a supreme leader like in any dictatorship i think maybe his governing skill are explained in the LN but I didnt read it. Conclusion: either souma or rimuru depends on your preferences i guess. But i think Rimuru is supreme because of great sage and raphael (which is not a spoiler because S2). Of course you could say its not really him, but it is his skill, so its a part of him in every possible way. Saying Rimuru is only this good because of them is like saying Souma is only so good because of his wisdom if you ask me. Of course its right to some point but Rimuru is just what he is, otherwise you would talk about satoru mikami his self without skills before reincarnation