Waterproof for UK winter

What's everyone's best suggestions for waterproof jackets for UK winter? My absolute favourite is the ronhill mercurial but I need a second option for when that wets out. Got a 100 miler in the Brecon beacons at the end of next month and the arc in January so it's inevitable they'll wet out at some point. Can't seem to find the jacket I want available so I'm looking for something else

I have used:

Janji rainrunner - shite, completely useless

Inov8 storm shell (original, thinking about trying the new one?) - not great, found it to wet out fast in heavy showers

Considering a hiking jacket for the second half at this point. Look more heavy duty and waterproof which I feel I'll probably need anyway for the second half. Expecting pace to slow a lot by halfway and it the weather's rough in the beacons, it's really rough

Would appreciate any input. Thanks all