The Evenflo Maestro is the least expensive of the bunch, but it is a fairly short booster and will require a dedicated booster afterwards (some kids will be able to move to a backless booster).
The Nautilus is the only one that converts to a backless booster. Some kids find the seat too shallow.
The Frontier can be a challenge to install.
There is no perfect seat, unfortunately -- you need to decide what's most important to you.
Carseat-checking (CPST) and WAH mama to a thirteen-year-old girl.