Britax Marathon or Boulevard or the Graco My Ride 65. But advice from friends wasn't good enough for me. I took it several steps further!
After getting real life advice from my friends, I hit up Lucie's List to see what Meg had to say about convertible car seats. I love her posts and find them to be generally incredibly helpful. She had several suggestions with the Britax Boulevard topping the charts (at least in terms of investment!). After Lucie's List, I checked out The Bump. I was already leaning towards the Britax Marathon or Boulevard, so I was excited to see the Marathon listed at the safest car seat. From there I checked amazon.com. I love reading reviews and enjoyed seeing that most people liked the Britax Marathon and Boulevard. I wasn't willing to pay to see Consumer Reports lists, but through some blog reading discovered that the Britax seats were rated very high.
We decided to go with the Britax Marathon as our main car seat. We opted for that over the Boulevard because the differences seemed almost exclusively for comfort and the price difference (about $30) didn't seem worth it. For our secondary vehicle, the one Wesley is only in occasionally, we opted for the Graco My Ride 65. It was consistently ranked just below the Britax Marathon so we were comfortable with that option.
We have had both car seats for over a year now and love both of them. We've had the Britax Marathon checked professionally and were told that it's one of the best on the market. It is one of the only seats that has a tether even when it is rear facing. The tether holds the seat to the frame of the front passenger seat, which makes the seat that much more secure. The Britax Marathon is a beast. It's a huge car seat but fits just fine in our Honda Accord. The Graco My Ride 65 is smaller and has less comforts (it isn't as padded and lacks the tether) but it does have cup holders and is much easier to install.
Overall, we are very pleased with both seats. We purchased both seats on amazon.com with free shipping. I've said this before and I'll say it again, if and when we have another baby, I will skip the infant car seat and go straight to the convertible. I love wearing my baby and found the infant seat to be heavy, cumbersome, and after 6 weeks stopped using it altogether. I know many disagree and prefer the infant carseat. It's just personal preference.
Here are a few other articles that are helpful in making sure that your baby is secure in their car seat:
How did you choose your car seat?