Britax Kidfix (not Kidfit) carseat rating is 77% and is a Best Buy.
HOWEVER, the Sunshine Monterey was rated 20%, and is a Which? "Don't Buy"
As that's a bit shocking, I'm reproducing the review here, so as to cover myself for libel!
"This group 2/3 seat is designed to carry children from 15 to 36kg (around 4 years old up to 12). The child travels forward-facing, and the seat can be installed using the Isofix mounts or the adult seat belt.
"We?ve rated this seat as a Don?t Buy because its protection in a side impact is so poor. This is because the instructions recommend you can remove the back rest for children over 15kg, leaving only a booster and minimal protection for the child if the car is struck from the side."
"Crash protection in a front collision is acceptable.
"The seat is fairly easy to install, though the belt routing is quite complicated. Strapping the child in the seat is straightforward
"The finish quality of this seat is excellent, but the cover isn?t machine-washable.
"Pros: Excellent finish quality, clear instructions.
"Cons: Very poor side crash protection, complicated belt routing, removing and cleaning the seat cover is complicated."