I cannot for the life of me think of any reason to play anything other than neutral. For one you get 60-70% the planet bonus that the evil choice will give you.
Most importantly, and this is DA specific, is the terraforming bonus. Immediately terraforming every square that you have the tech for is insanely powerful. The amount of money saved is monumental. When you compare that with the advantages you get for choosing evil or good....its way overpowered.
Now, I don't want to suggest getting rid of that. I think its just that good and evil suck, not that neutral is overpowered. Just wondering if anyone else thought the same.