We are a Britax family. Case in point:
Roo in her Marathon, Jasper in his Boulevard. They're like plush recliners for your kids, only with the added bonus of protecting them in the event of a crash. In fact, these carseats are so well-designed, they have been known to keep children safe even when the car they are riding in has been struck by a train! (I would still recommend not stopping on train tracks, in case you were considering doing some home-testing.) That seat was a Roundabout, a convertible seat that is good for rear-facing infants to 40 lb forward-facing kiddos.
We went with the Marathon when Roo was a baby because it has such a long lifespan. Britax carseats are not cheap but they are extremely well-rated and in our experience they are just as durable as they are plush and good-looking. When Jasper outgrew his infant carrier (at six months!), I discovered a new Britax convertible seat. The Boulevard is even cushier than the very similar Marathon (both seats are recommended for children up to 65 lbs) and my hands-down favorite feature for Jasper has been the No Re-thread Harness Adjustment which allows you to adjust the harness height without having to re-thread the harness straps– super handy when you have a rapidly-growing baby/toddler/kid. Roo was a much more gradual grower so it's not as much of an issue to have to switch out the harness height every six months or so when you pull the cover off to wash it.
We recently received a new Britax model, the Marathon CS. The "CS" refers to the Click & Safe audible indicator that helps to determine when the child seat harness is within range of appropriate snugness. I remember taking a carseat safety class when I was pregnant with Roo and being informed that an alarmingly high number of parents were installing their seats improperly AND using the harnesses incorrectly, as well. I think it might have been close to 70%! The Marathon CS is just as comfy and sturdy as its non-clicking predecessor but it does give me a reassuring feeling to know that there is a way to make sure the harness is optimally tightened. Especially since this seat is going to go in grandma's car…
The Click & Safe feature is also available in the Boulevard CS. (Did I mention how totally awesome that No Re-thread Harness Adjustment is for wiggly boys?) The Britax Marathon CS has a MSRP of (USD) $299.99 and can be found wherever quality baby goods are sold.