K.R.
this is going to be a matter of opinion b/c the government standard is a pass/fail, not a rating or ranking.
Just based on inspecting the various seats in the store, I'd say the "air" seat is pretty cool! Press your fingers into it and feel for yourself the cushion there versus in the foam sides of other seats. Also look at how deep the sides are.
You may like deep sides for protection, but some kids don't like them because they can't see and it is harder for mom/dad to position and buckle baby in.
Personally, I don't see the appeal of many Britax seats, except ones like the Boulevard which has good sides. I also am in love The First Years True Fit seat--I have 2 of those--and will vouch for the ability to install RFing correctly by myself.
Some seats don't fit in all cars or seat positions. Make sure whatever you pick fits well and is installed properly.