which of these bikes?

aircooleddude Posts: 79
edited May 2013 in Road buying advice

I'm looking at buying one of these and would like to know which people would recommend.

Cannondale Synapse 2300 2013
Specialized Allez 2013
Cannondale Caad8 2300 2013
Giant Defy 4 2013

Any advice would be greatly appreciated. I know the CAAD8 is more of an aggressive riding position but I don't mind as long as it's fairly comfortable. This will be used as a second road bike. I mainly ride 40-80 mile at a time and it will be used as a stand in. Sadly the budget will not stretch to any more! My budget is £600 and if anybody can recommend a better bike within budget then I'm all ears!