I just went through this excercise myself. I opted for the Quick 2.
I tried the Quick 3, the Trek 7.5 FX and the Gary Fisher Mendota. All had nearly equivilent rides in terms of road vibration, but the quick felt, well, quicker. Riding it around town, it felt quick off the mark, and very responsive - I felt more "kidlike" riding this bike, and it seemed more fun. On the Trek, I felt that it didn't respond to my handling quite as well. I also think that the Trek kind of looks pretty standard - and to my eye it had too many visible welds. The Cannondale frame looked very sleek and smooth.
As others have posted though, it ultimately is about how the bike feels. Since you are new to bikes, whether the shifters are push / pull, or push / push, it will make no difference. You get used to that stuff very quickly. The best thing to do is try them all first, and then make a decision.