I've had a pair of Sunderland of Scotland waterproof trousers for years - found them balled up in a hideous, muddy heap in an old tack room I took over about 4 years ago (so well worn and abused then). Washed them well in waterproofing solution and they're still going strong. I wear them all the time and they never leak, are warm, comfortable and cope with everything I've thrown at them (horse riding, dog walking, sheep wrangling, mucking out the pigs, etc...)
I'm so impressed with them that I bought my OH a pair this year and he's over the moon with his too - previously, he'd get through waterproofs like they were going out of fashion, end up wet and grumpy and chuck them out. He loves these ones and if they last half as well as mine, I'll be very happy.
Not the cheapest, but definitely the best I've ever come across:
https://www.glenmuir.com/sunderland/Re: wellies...tough call. 5 or so years ago I'd have said Muck Boots but I threw my last pair away a week ago at only 18 months old, having worn right through the back of them. Not impressed. Am back to wearing my £10 Dunlop wellies with very thick socks and they're doing far better than the Muck Boots did. My OH has just got himself a pair of Skellerup wellies which he says are fab so far, but time will tell.