At the highest level is a funny way to say it because we do it know what the highest level is. Go players are generally more matured emotionally and definitely more friendly.
The intellect is important but not as important than wisdom.
And to compare complexity is futile as they are different games but if you must then it must be compared at their standard board and in this case the possibilities in go far exceed chess.
Chess is a game that is further evolved than Go. But it is not simply due to the board size.
Chess has evolved at a far quicker rate due to the growth of Europe and the Americas, and that played a massive role in the understanding of it. Go, on the other hand, was like many games banned by Chairman Mao, and most of the best players had to leave the city for the countryside in their resettlement programs. The only real player was Japan, and they only had a simple understanding of the game.
The last one hundred years have resulted in most of the openings and half of the middle game ideas in chess already being understood by humans. We did not need Stockfish to understand this part of the game. The middle game and the end game is the real fertile ground for the chess engine of today.
Alpha Go, on the other hand, has shown the Go masters that they understand very little about the game and big inroads are now underway, but this progress was hampered by the social conditions in Asia, and not the Go players' mind or how hard the game is.