Can anybody advise on car seats?

[shadycharacter]

DS is currently in a Britax freeway but I was looking at getting him a new seat.

Have been doing lots of reading and apparently he needs to go in a high back booster next, so there's no point buying a new seat until later on in the year when he's 4.
I hate these kind of seats, I'd really prefer him to have a harness but can't find any seats with harnesses for 4+ yr olds. Anyone know a way around this?

Anyway, so far I've shortlisted:

Maxi cosi Rodi AP Air Protect 15-36kg
sunshine kids monterey 18-36kg
Britax adventure 15-36kg
the volvo seat 15-36kg

Really wanted to put him rfing but since most of the seats are to be turned ffing at 4 yrs, I don't think there's much point spending £250 on a seat that will have to be used just as a £60 one would anyway!

Anybody got any recommendations?

We've got a Britax Evolva 123. I believe you can use it with the 5-point harness up to 15kg. It is really padded and DD seems pretty secure sideways as the pads move in/out to give a good width fitting. Plus, I plan to keep DD in the harness until she's 15kg regardless of her age.

we have the maxi cosi rodi xr and it seems comfy and supportive

It will be 18 I think rather than 15 - 15 is the minimum for a HBB not the max for group 1 :)

Britax Two Way Elite?

We have this and it can be rear facing with harness up until 25kg's so approx 6yrs?