H.B.
I have the Nautilus for both of my kids and love it. I also love the fact that it is the last carseat I will ever have to buy...wish I had gotten it sooner. I don't know much about the Boulevard, but when my daughter was younger, we had the Britax Roundabout, and I know that Britax is supposed to be safer than most, but it really seemed no better than any other carseat we've had...imho.