Leonidas is a figure who's deeds are recorded in typical Greek fashion. That is to say his deeds are both exaggerated and romanticized. Greatness is more palatable in the figure of Alexander 2. I question some of the accomplishments accredited to him, but consider his colloquial title to be reasonable.
I would place Themistocles far above Leonidas and consider his accomplishments more significant from a Greek perspective than those of Alexander 2.