Convertible or infant car seat?

Jenesis
Any good brands for Convertible Car Seats? Your experience if you have used one since the beginning? 
I am having baby number two and we have been thinking about getting a convertible car seat right away instead of an infant one. With my first born we got tired easily getting the infant car seat in and out of the car all the time and now with our second baby on the way and having a two year old we aren't too sure if an infant car seat is a good idea...