Besafe Stretch B is plus tested. The Besafe infant insert is also really really great.
You can use the two Britax ones from birth if you get the newborn inserts. Bear in mind that they are both on offer at the moment, and aren't usually that price.
Avionaut Sky might be worth a look?
A 75cm limit for an infant carrier won't matter, if you want to swap to an ERF seat from ~3m (this is realistically 4-6 months - they need to be able to support their own head a bit, sit with support in a reclined position, basically be comfortable in a car seat without an infant insert.
Joie Juva is a perfectly fine infant car seat and costs about £60, if you didn't want to get one with a pram or find an infant insert.
In general you want your car seat to do one job, maybe 2, I've never come across a car seat which does 3+ jobs and does them all well. Two is definitely doable, but the fewer the better.
Newborn up to about 4 months is one job - there is something about the recline angle needed and the snugness of the fit which is difficult to combine with many other things.
Then rear facing, particularly into toddlerhood and beyond is another job.
Forward facing with 5 point harness is another job.
Belt positioning booster is a different job again.
They just all have different needs, and it's physically impossible to optimise for 3-4 of these at once because some of them directly contradict each other. You can sometimes bridge the needs between two close-by settings, e.g. most infant carriers do well for newborns and the baby RF period, though they don't last long enough to ERF. Spin seats are often good for RF and for FF but they don't usually fit newborns very well (sometimes, they can). Seats which turn from a forward facing, 5 point harness into a booster are usually better performing compared to "all stages" seats.