I have been using a Britax b-safe careseat with my 5 month old since he was born. Its sturdy and clicks into its base or stroller very easily. Only thing is that its pretty heavy and bulky so as my son gets bigger, my hubby has to do all the lifting.
Cybex aton 2 is safest, chicco is next. I have a combi. Safety 1st does well in crash tests as well, maxi cosi in the us is made by safety first so there no point in spending extra on one. Carseat.org is a great, yet over whelming resource. Consumer reports does independent (much better and thorough) crash test rating. US crash test standards are terrible and only give a pass/fail rating! Graco always has recalls and are cumbersome to carry, I will never use them again.
Peg perego is very well made. Chicco Key Fit is also a pretty good one.
Safety 1st is a great brand and even Flo is good too.
A car seat that was light weight was important to me. I didn't want something too expensive either. I chose a graco travel system.
I have an urbani amd I love it. It's lighter then most car seats and has a stroller set that folds up very very small