Siberian tigers are generally recognized as the largest big cats. That said, one tiger compared to another, one tiger, only proves that, with that particular pair, one is bigger than the other. For more accurate comparisons, at least a dozen of each variety would need to be measured and weighed, then all data averaged and compared. They would all need to be at, or around their prime ages and healthy.
This makes me wonder where are we humans going wrong? We have a society, we have the concept of marriage, we have rules and regulations designed for us to live a happy life. Yet we are still searching for pure love and look at these animals they do not have anything and the love between them is so pure.