I have seen people suggest Lula as the Brazilian leader. I too would argue this would make much more sense, but him being a recent leader probably rules that out in terms of possible leaders (at least for a few decades, if the series goes on that long).
Those people were just joking . The most common, serious suggestions besides Pedro II are Getúlio Vargas and Juscelino Kubitschek. Personally, I think Pedro II is head and shoulders above both of them.
Pedro makes even Catherine De Medicis look like Julius Caesar in terms of the power he yielded- France had about 16 million people in her time (she died in 1589) whilst Brazil had about the same in Pedro's time, and he died in 1890, more than 300 years later. In Pedro's time, France and the U.K. Both had 30-something million people. In terms of other South American Civs, there were around 12 million people in people in the Inca empire in 1438, over 450 years earlier.
It was probably even less than 16 million, yet it was alright for Latin America's 19th century standards.
Pedro II and the Empire were able to keep Brazil together through the 19th century. That may not sound like much, but most of the former Iberian colonies fragmented due to internal pressure, or lost their territories due to external pressure. Today's Brazil could easily be a dozen of small countries.