Have a look around Moto Mate in Rivonia, I still kick myself when I
see some of the same things I have going for way less than I paid
there, even against other Moto Mates. That's about the closest you
can get in narrowing your options outside of real world testing/use.
And so for other stores too.
It's hard to try and recommend things that have great reviews
elsewhere or online and are not available here and not at the same
price if so either.
With visors though, it's said they can be a little less safe if
you're really that specific, as with the hollow in the helmet for the
visor to retract/extend.
I would have liked one, sunglasses that fit well on your face don't
always fit well inside a helmet. I'd take note of the mechanism on
the visor too, it's something that could wear poorly or even break if
the helmet has an overcomplicated mechanism or bad design for that.