In reply to Getoiu:
Some good answers here from others. I run very hot and personally find that even soft shells sweat out from inside, so I don't use them much, unless it's either very cold (like the Alps) or I'll be moving very slowly and there's little chance of rain. Generally this would be for climbing where the stretch and abrasion resistance make them better than a hardshell. However, even then I always carry a full set of hard shell jacket and pants in my pack (even in the hottest of weather) just in case it all goes pear shaped and you're stuck on a mountain for the night.
Personally I use a pair of Berghaus Paclite pants, full zip which is great for getting them on and off over muddy shoes/boots or crampons, and they weigh very little. They can tear on sharp rocks fairly easy though so you have to be careful, but duct tape inside and out over the rip is a cheap fix there.
For a jacket, I bring either an old North Face goretex jacket that's light and does the job, or an even older Patagonia top with some proprietary fabric that has a bigger hood if I'm going to be wearing a helmet. They're both fairly light, about 350g or 400g and don't have many frills, but keep the rain off well. I don't bother with pit zips but I like a jacket with large hand pockets because they can be used to help vent and I like to walk with my hands in the pockets when I'm going easy. Make sure the pockets on any jacket you buy will clear a hip belt, or harness if you climb.
I find most decent goretex jackets do what they say on the tin, and would choose one on how they fit you personally, how the hood works, how much extra weight you're willing to carry around, and budget. If money is no object you really can't go wrong with Arc'Teryx stuff, in my humble opinion they're about as good as you can get, from the fit to the warranty, but most reputable brands do good jackets that will do you fine.
I have mates that use super lightweight rain jackets like OMM Kamleikas, but they don't leave me feeling confident that they'd survive an all day downpour, so I wouldn't bring them as my only waterproof, but that's just me. I often bring a lightweight windproof though, they only weigh aabout 100g, for when a baselayer alone isn't enough to cut the chill, but when I don't need to go full waterproof.