The rotation everyone means when they say 'rotating car seat' — true one-hand spin, extended rear-facing, and it lasts from newborn to booster.
If you buy one rotating seat, this is the safe default. The 360 rotation is genuinely one-handed — you pull a single lever and the shell swings to the door, which is the whole point when you've got a screaming newborn and a bad back. It rear-faces to 50 lb, which lets most kids stay rear-facing (the safest position) well past age 2 as NHTSA and the AAP recommend, then converts forward and finally to a belt-positioning booster to 120 lb, so it's realistically the only seat you buy. Downsides worth knowing: it's heavy (~30 lb) and bulky, so it eats a lot of legroom in front of it and is a pain to move between cars. Skip it if you have a compact car with a tall front-seat driver, or if you're buying a lightweight seat you'll shuffle between two vehicles weekly — a rotating seat is not that.