question about carseat

So this will be my 3rd kid and we're have been talking about car seats and which one is best well I came across one I really like and it can last a very long time from birth to 6yrs- with my other two I got a normal infant car seat with the base and all that I was hoping for some feed back on getting this one and when it's time to get baby out just baby wear....would it be worth it or just go ahead and get the kind with the base in and out of the car car seat? Help!!!