Here are my advice about buying the 'best'carseat...
The best carseat is the one that fits in your vehicle tight and easily, that fits your child nicely and with room to grow, that can be used by you easily and correctly everytime. By that definition, brand name doesn't come into play. In addition, all carseats sold in Canada meets minimum Canadian safety standards.
Not all carseats fit well or easily in all cars. So when you shop for a carseat, you should try it with baby in it to see if he/she fits well in the carseat with room to grow and that the carseat can be installed tightly in your vehicle. Or make sure you buy from a store that you can refund should it does not fit in your car.
Having said all that, the reality is somewhat different than 'text book'...
There are a wide range of convertible carseats out there with different safety, comfort and convenient features and costs vary from approx. $100 to $350.
There are the Cosco Touriva/Scenera and Evenflo Tribute that are the basic models. Then there are the Graco Comfortsport, Evenflo Victory V that are their 'deluxe' models. The 3-in-1s such as the Cosco Alpha Omega Elite, Eddie Bauer 3-in-1 Deluxe, Safety 1st Intera, etc. And of course, the Britax Marathon and Roundabout.
The Marathon is better in many regards. It has the longest seatback and highest harness slots which mean your child can be in it longer than a carseat with low harness slots or short seatback. If you don't know why, I'll explain later, if you'd like.
The Marathon is also the only seat that can be rf and then ff to 48 lbs in Canada. The Marathon is also very easy to install and to fit in many cars. The small cars usually have problems with other carseats, but the Marathon with a higher base and smaller foot print seems to fit well in many too. There are many other attributes that make the Marathon worth it, imho.
Many parents like the 3-in-1 (rf, ff and booster) seats thinking it would be the only seat they would ever need for baby's carseat-riding career. This often is not the case because tall/long-torso kids outgrow this type of carseat because of its shorter seatback and lower harness slots or heavy kids (more than 40 lbs) but too young to sit in a booster w/ just a seatbelt.
Bottom line is just be try out the seats in your car, with baby, etc. as much as possible before buying a carseat.
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TamC
Certified Canadian CRS Technician