I have only tried one car seat and it was OK, it has the inflatable cushion at the bottom. THe only thing i didn't like is that I have to re-inflate the cushion often, it only fits in the front seat and if you have a furbaby that likes to look out the window it isn't the best. HTH... I'm looking to buy a new one too.
this is the one I have.
Booster Seat