I do NOT recommend the Graco Nautilus..... it is a great seat, but the recline is barely there. you'd think it was great since it has that recline positioner at the bottom... but even fully reclined, my 3yr old falls asleep and his head plops forward, waking him up.... I have younger kids too .. all the same issue. I only use if for daytime and awake travel. The only thing I do like is the built in cup holder.
by comparison, my Britax Marathon and Britax Boulevard carseats go to around 65 lbs and all my kids sleep like a baby in them. Very safe, 5-point harness, and good recline for sleeping.
To make a best pick, I would say the Britax Boulevard !