We went middle of the road and got the Dash. I liked the lighter weight of the Vibe (the top one) and the breaking mechanism, but didn't think those things were worth the extra money (about $150 extra). We found the brakes on the sport (base model) too awkward. We like the way the dash folds up and it has a handle which is good for lifting it in and out of the car.
Best thing I reckon is to go into a shop and try out a few and see what you like about each model. Only bummer is that they are pretty expensive. The dash cost us about $650 I think? And the toddler seat was an extra $100 or $120 (?) - my folks gave that to us as a gift when P was born. And the UV/Bug cover was an extra $70. So it all adds up. But I am still glad we spent the dough.