Ashoka was way ahead of his time as a King and Emperor. In 268 BCE he became the emperor of Magadha. Compared to Akbar whose coronation happened in 1556. That is some 1824 years later. While Akbar's claim to fame is all about his religious tolerance something that can be challenged as Jazia was imposed on Hindus Ashoka talked about not just religious tolerence but Human rights, Animal rights, preservation of forests and natural habitat. His edicts had messages that was beyond anything the world will see more 2000 years later until the UN charter. Akbar though Great in his own way doesn't stand anywhere near Ashoka. That is the reason why our founding fathers looked at his principles while laying the foundation for this country.
I am not debating that Ashoka at his death left his kingdom weakened. This is quite possible. We don't really know because the only reason we know about Ashoka is through his edicts and they don't mention what happened in his later live. So later part of history is derived through other sources. But even then Kings in India have always been celebrated for being Just, righteous and true rather than their Valour and their ability to wage war. So may be by international standards you can say he may not be great but from Indian standards Ashoka was nothing but Great.