I've tried all sorts of waterproofs over the years and I've found that the
altura night visions stuff is as good as anything. You need to keep up with the cleaning and reproofing stuff. My favourite overtrousers are night vision. But I don't tend to bother about my legs too much and have been known to use regular waterproof trousers and wrap insulation tape around them to keep them out of the chain.
As someone has pointed out already the problem with waterproof stuff is the big holes in it that you need to put it on. I'm yet to find anything that keeps me truely dry either the rain gets in or the sweat doesn't get out. I've got a Boardman waterproof jacket that cost £15;in a sale thats every bit as good as a £120 jacket. Think about pockets too, if you are wet and cold with soggy gloves your dexterity will suffer. The aforementioned Boardman has no pockets and fiddling for gate keys or work passes under layers is a pain.
I now take the approach that I don't mind being wet as long as I am warm, so build layers with that in mind and then put a waterproof top layer on.
I've yet to find any decent gloves that will keep me dry on my half our commute. The expensive stuff seems to fare only marginally better than the likes of Aldi stuff. My favourite are planet X lobster claws that I got for £8 a pair but they leak.
Sealskinz don't do it for me and were a big disappointment.
Size up with gloves, I have a pet theory that it's the stretching of the stitches allows water in.