EVO will give you better platform to upgrade; however, you'll have to drop a lot of money.
CAAD10 3 will come with very solid components right away. No cost to upgrade. CAAD10 isn't necessarily a bad frame, but if you're counting grams, I think the EVO is ~100g lighter, so it'll be easier to build a lighterweight build on over the CAAD10.
FYI, I was deciding between a 2012 CAAD103 and 2012 Supersix 6. With the extra cash from the Supersix, I could've bought some really nice wheels or a new crankset or even a 5 piece drivetrain upgrade kit. I opted for the CAAD10 and regret nothing. I've been infected with upgraditis. I can't imagine how bad it would be if I had the lower grade components.