Well, you can't seem to support your argument that "A" maximally great being must exist. You can show that in several categories, something must be the greatest being 'in that category' but you haven't given anyone a reason to think that there MUST be one being that is greatest in more than one category. So, you keep playing with words and pretending you've made a point, while ducking all criticisms.
Good apologist, though.
Why do you think we have to only take one category at a time?
I gave you the example of Usain Bolt versus Stephen Hawking.
If they were both equally great physicists and only one of them held the world record for land speed, then Usain Bolt beats Stephen Hawking.
If they BOTH had the same number of Nobel Prizes and Olympic Gold Medals and only one of them could truthfully claim moral perfection then THAT would be the differential.
You can keep on adding superlatives in competition with each other, singing ..anything Hawking can do Bolt can do better, but eventually you 'max out' your greatness of being.
And all the while, you must stick with the necessity of existence, because you can't "be" the MGB unless you actually "be".
And you must admit the notion that if God is omnipotent, then nothing trumps God. (Apart from another omnipotent being - who has always existed and always will.)