I found when learning to program, that 2d was a lot easier to learn the basic principles with, and then once you figured out the meat behind programming and flow and all that, you could tackle 3d which made perspectives a lot easier and made your game look more professional. 2d is a much more controlled environment, and sometimes new guys need that. Do both, then which ever one scares you or confuses you the most, leave it until later, or in the case of 2d never.
Juvenile Industries
Current Project: KillZone(FPS)
Soon to come:An rts, and a snowball fight game