How can it get really cold and wet? Or does the OP live on a moon of Saturn?
To be honest, I don’t think you can really quantify it just in temperatures.
For example, you can go out in sub zero-conditions, mild day, sun out, and have toasty hands all day. Then you can go out in +5 celcius, driving wind and rain, and stone cold hands – having to remove gloves every 5 mins just to warm your hands up! I often find it is the days near freezing that are the worst. Not the ones below.
Same goes for the type of riding you do. An hours MTB ride around the woods is nothing like a ride high up in the open hills, where something as little as a change in direction can change your condition from toasty to icy within seconds.
And on those points, it’s difficult to interpret reviews, because actual temperatures mean very little. It’s like measuring your fitness based on average speed, knowing nothing about terrain.
My own biggest problem with gloves appears to be waterproofing. My hands mostly get cold once wet, and also with wind chill. And I’m yet to find a glove that is actually waterproof like it claims to be, especially around the palms. A showerproof glove is fine for an hour, but not an all-dayer in torrential rain.
Thanks for the suggestions so far btw. Still completely undecided and not yet convinced by neoprene gloves.