I did a convertible with my first baby and an infant with my second. I would definitely suggest the convertible. I only said yes to the infant (husband wanted it) because he was a winter baby. The only time the seat is out of the car is to and from house to car. My neighbor had a baby that would wake up at the slightest touch, but I never have had trouble transferring my kids from the carseat to my carriers.
I'm of no help with the strollers since I didn't use one with my daughter until she was almost a year and haven't put my son in it yet. I just got a cheap (short since I'm short) umbrella stroller from Target, but I don't remember the brand since that was four years ago.