Best multi-stage carseat for toddler?

We are getting ready to move to the UK with our almost 2 year old. Been doing some research to figure out which of the multi-stage carseats is best for him since the brand we use in the US is not available there, but I would like to hear from anyone who has some experience. He is already 13.6kg and quite tall, so he's been sitting forward-facing for a little while. I would like to get a seat that will grow with him as long as he needs one and not have to buy again. So far I have found the Joie every stage and the Graco milestone all-in-one as seats that might fit this criteria--anyone own either of these? Or any other suggestions of a good one I've overlooked? I'm a little shocked that I've had so much trouble finding verifiable safety ratings, it wasn't this difficult for the two seats I bought here! I'm pregnant with #2 as well, so if anyone has a suggestion for an infant seat I'll take that also! Thanks!