>...George Soros, who's donated far more money and influenced far more country's politics...

Prior to 2012, that was probably true:

http://www.opensecrets.org/news/2010/09/opensecrets-battle-k...

But since then, the Koch brothers really ramped it up. The Koch brothers spent an estimated $412MM in the 2012 election alone, about an order of magnitude more than the amount Soros spent in the entire previous decade:

http://www.thenation.com/article/koch-brothers-spent-twice-m...

Combine the $412MM they spent in 2012 with the $900MM they want to spend in 2016, and that's ~$1.3 billion this decade, compared to Soros's ~$40 million in the last. That's not even close to the same level. And I haven't found any evidence that Soros is spending at the same level as the Koch brothers this decade.