We have had THREE kinds of convertible seats before settling on a Britax. First we got the Evenflo Triumph based on Consumer Reports recommendations at the time (2005). That seat was a nightmare - truly the worst seat. Ever. It was hard to get our little girl into, hard to tighten and then would slip off her shoulders before we would get home (basically not protecting her at all)! I actually stopped subscribing to CR after that car seat because they really got it wrong. I've also talked to other mothers and professional car seat installers, and they too hate that seat. I only know 1 person that didn't have the same problems with the straps that the rest of us had.
After a few days of that seat, we switched to the Graco Comfortsport. Graco and Britax are the only two seats that pass safety standards in all countries and are also airline safe. We had used the Comfortsport for over a year and mostly liked it. We didn't have latch in our car and left our little girl backwards until she was almost 3 (after doing tons of research and finding how much safer it is for kids to be backwards as long as possible). We would have waited to turn her forward until her 3rd birthday, but we got a new car the month prior to her birthday and figured it would be best to make the transition then.
The thing that really bugged me about the seat is that the seat-belt would pull on it and it would soon be leaning to the side so we had to re-install it often (which was never easy). Also, our little girl is SMALL and she was already too tall to keep her backwards even though she was only 24 pounds. So, we gave that one to my dad when he moved up here and got that Britax that we always wanted but didn't want to spend the money on. I want to point out that we never could get the Graco installed in my dad's Suburban facing backwards (in fact, my dad sliced his knuckle on the edges trying to get it in) so it was always forward in his car. After using our new Britax, he ditched the Graco and purchased a Britax Marathon.
So I clearly recommend spending the money on a Britax. They're FANTASTIC! We checked out the different styles at Babies-R-Us and purchased the larger, Boulevard (which is the same as the Marathon, but with extra side-impact protection). Go test them out, put your baby in the seats and try them in your car. Choose the largest style that will fit your baby and your car. Then order it from www.AlbeeBaby.com (the best price around, always at least one color on sale, FREE shipping and no tax to WA). :-D We lucked out, we ordered ours the week before Christmas 2007 and they happened to have a Boulevard for $10-20 more than the Marathon so we went for it. But the Marathon is almost the same, just as nice, safe and easy to use. Oh, and installation is a dream - whether or not you have LATCH. My husband and I would be at each other's throats trying to get the other seats tight enough in our car. He can install the Britax by himself because there are clips on the side that hold the belt tight once you've tightened the belt.
Our daughter is way more secure, it has extra side-impact protection (on our model) and it has never loosened, slipped, etc. It also fits her better than any of the other seats. We have had it for over a year (it still looks new - well, expect for the crumbs ;-) ) and we plan on using it for quite a few more years.
Also, I would like to point out that I know 2 other mothers who have done the same thing and we all wish we had just saved the time and money and started with a Britax. Our daughter will be in this seat years longer than she would have been in the Comfortsport (saving money) and when we move to a booster down the road, it too will be a Britax. Go Britax! ;-)