Each race has its own strengths and weaknesses, some races appear stronger in comparision to others, but when you look at the whole picture the races are well balanced.
This gives the game enormous amounts of replayablity, as you can try many things with many races, and for challenges try things against your race's grain (ex. diplomatic Dregin).
Since each race has it's own niche (ex. manufacturing, diplomatic... ect) the question i'm posing isn't which is the best military race, nor is it which race is best technologically or in the late game, it's which race (in your opinion) is the best overall race . Since there is much variations within a chosen race with racial abilities, so include them in your pick.
For the sake of comparibility, can we assume super abilities are turned on, and i would ask to disclude custom races.