Car Seats: Isofix advice please?

[flowertot]

We want to buy DD (3 years) a new car seat. At this stage, are isofix ones the safer options to get? I believe they are for the rear facing seats and for the next size up, but not sure at this stage. Or is it a marketing gimmick anyway? We are about to get a new car with isofix so its no problem but just want to get the safest seat there is for her.Thanks in advance for advice

Does isofix just make it easier to fit seat properly or is it a genuinley safer way to tracel?

will she still be using a a harness seat?

ISOFIX for stage 1 and 2 is the safest way to travel. not so much for stage 3.

Again I wasn't sure whether a harness seat is better or one using the adult seat belt. Any idea? There doesn't seem to be much info out there. She can easily fit a booster type seat with adult belt but wondering if that is the best option?

If she's under 18kg a harness is recommended.

She is 18kg so looking for next seat up as she has outgrown the last. Guess adult seat belt safe as any then?