Depends what you want to do with it really. If you're planning on using Django or Python Image Library, start with 2.7. If you're not using any dependencies or

Depends what you want to do with it really. If you're planning on using Django or Python Image Library, start with 2.7. If you're not using any dependencies or frameworks relying on older versions, start with 3. Either way, as long as you work at it continuously, moving backwards or forwards won't throw you off too much.