Car seat transition

When did you ladies switch your child from the infant car seat to the next step up and do you do rear facing or forward facing? From what I read the rear facing as long as possible is safer. My 18 month old is still in a infant but he still meets the guidelines to stay in it but not for much longer.. he is 27-28 pounds and his head doesnt come up past the back of the seat but I feel like it may be safer going to regular car seat. I see all different information out there about weight limits etc. I live in California if that makes a difference. Also there are so many options for car seat! What is your favorite and why? It's a bit overwhelming. I have to buy for at least two cars, maybe three so looking for one that may be easy to take in and out so that maybe I could save some money and only buy one or two. I know my infant car seat is a son of a **** to take out often so I bought a few. But the next step up for car seats a pricey.