Wikepedia's list is missing certain Gedolim. Where can I access a list of Gedolim that would be virtually unarguable?
Virtually unarguable? God Himself is called "Gadol" by King David in Psalm 145:3. To this day, I don't think anyone would disagree on that one.
גדול יהוה ומהלל מאד ולגדלתו אין חקר
The Lord is great and very much praised, and His greatness cannot be searched.