There are two Maraji that are commonly known as the most knowledgeables Maraji today. Unfortunately, I'm not able to choose between them because I don't have enough knowledgement to do so. Even if I refer to other scholars, there is a difference of opinion in which one of them is the A'lam. How should I proceed in this case?

If you believe both of them to be on the same level in light of advice from religious scholars, then you must follow both, and where there is a difference in opinion you have to take the stricter opinion (haraam/makrooh, wajib/mustahab) etc.