generally speaking you get what you pay for,
so if you buy cheap PVC jacket and pants, they will be waterproof but you will sweat like crazy!
if you spend £300 on a jacket you will have a jacket suitable for winter mountineering.
my suggestion is get out and try on as many as you can, some will feel more comfortable, some will feel terrible.
most gear is breathable today, the more you spend the better it breathes!
but remember, you can buy the most expensive Goretex XCR jacket, but block the pores (microscopic holes, like on your skin) and it will work just like a PVC jacket!
note: most mountineering jackets have zips under the arms, to allow air to cool you, even today they still can't cope aswell as your own skin!
take the most expensive jacket run up a hill, you will still sweat!
as i say try on as many as possible, don't be fooled by gimmicks, and any good salesman will let you take it home to try(and bring back).
lastly, check the label!
is it waterproof,
anything that says:
weatherproof, water resistant, or showerproof, is not 100% waterproof!
have fun and choose well!