[Gryphin]

Build your colony ships with only 3 engines and 2 cargo bays.
Reasons:
Build in 2 turns instead of 3
Moves more population to start your new colony
The home planet will replace the population fairly quickly
The 2 squares lost in speed is negligable compared to the 2/3 build speed. I'm not the math type but I'm sure someone here can post it for me.