If intelligence is good for every environment, we would see a trend in the encephalization quotient among all organisms as a function of time. The data does not show that. The evidence on Earth points to exactly the opposite conclusion. Earth had independent experiments in evolution thanks to continental drift. New Zealand, Madagascar, India, South America... half a dozen experiments over 10, 20, 50, even 100 million years of independent evolution did not produce anything that was more human-like than when it started. So it's a silly idea to think that species will evolve toward us.
In a word cetaceans. Some have bigger brains than humans.
The encephalization quotient that Galaxy cites isn't a direct measure of brain size, it's a ratio of actual brain mass to the value that a mammal is expected to need in order to manage things like breathing and coordinating body movements. Cetaceans and particularly dolphins do have some of the beefiest brains among mammals in terms of EQ, but humans still beat them by a wide margin.
"The Planet-of-the-Apes Hypothesis" Revisited --Will Intelligence be a Constant in the Universe?