For a long time, Child Passenger Safety Techs were told not to recommend specific seats. They are all safe and pass federal standards, or so said the official training manual. Most techs dutifully passed this stale company line along to parents. Fortunately, that all ended when the NHTSA itself started rating seats a number of years ago. At last, official proof that all carseats are not created equal! The original ratings were questionable and almost every seat got 4-stars or 5-stars, so they were not really useful. Now, the ratings have improved and have a wide variation among models. They don’t always match the experience of technicians and advocates, but they are worth a look.
The big drawback? They don’t actually do any crash testing or correlate the star rating to a risk of injury.