My top pick is the Britax Marathon . Ask nearly any owner and they’ll have nothing but praise for this seat. Britax puts a lot of effort into making sure their instructions are clear and their seats are as easy as possible to install and secure your child in. Steel bars are used to reinforce the structure and side impact protection is built in. The Marathon has a large range of adjustment and will fit children up to 40 pounds rear facing, or 65 pounds and 49” front facing. The fabric is easily cleaned and very comfortable for extended trips. While the full Britax convertible car seat line is excellent (including the Advocate and Boulevard ) I feel the Marathon is the best value.
Note: If you plan to travel a lot with your seat, or frequently move it between cars, Britax also offers a ClickTight version of their Advocate , Boulevard , and Marathon seats. Though heavier and a little more costly, these seats are MUCH quicker to install with a seat belt – taking seconds rather than minutes.