We have had a fair number over the years most still in use. Started with the eldest in a 2nd hand(I know that isn’t a good idea but the oh was a single parent on benefits) infant Carrier. He was then moved into the Joie stages and rear faced until he as 3 and a bit changed to front due to not fitting in the car and the oh being pregnant and struggling to get him in. Now he is front facing in a britax advancafix 2 (isofix with top tether and belt options) as it had the longest time in a 5 point harness without spending silly money getting a Swedish seat.
The youngest started in a Joie igemm on the Joie advanced base which has allowed us to move him again rear facing to the Joie iadvanced without having to shell out for another base.
After all the research we did when getting the youngests seat the change in legislation to isize made very little difference to us. It just meant we needed to ensure the seat was isofix rather that belt attached. The issue was the lack of products from the manufacturers which meant we stuck with joie.
Looking forward to seeing others views. Especially on extended rear facing.