All of the machines you've mentionned are very good... So much so, that it's really a choice of "which bike shop do you like and trust?" I like Specialized's bikes, but I ride a Trek... because the Trek shop owner and I are friends, and the only Specialized bikes available here are via internet or mail-order. Cannondale bikes are very well assembled, also. Perhaps next time I "need" a bike...
Look for the best grade component group and the lightest weight in your price range. It'll all be Shimano this or that, but low-end Shimano parts can be miserable to live with. Likewise, a beautiful but heavy bike can be a tin pig on the trail.
Ride the bike before you commit... the salesman won't say no... although, if you leave a credit card with him, you can go farther than just an obligatory ride 'round the block. Is the bike last year's model? If so, then negotiate a sale price... often, the only differences from the latest ones are cosmetic.
See what the dealer will "include" with the sale... helmet? rear rack? shorts, perhaps? Establish a good relationship with the shop, and they'll fettle your bike for years to come... something that is unavailable at any price when dealing with a department store... or a web site.