If your concerned with water or slush, have a look at Michelins Alpin range. Xice are considered "scandinavian" tyres on our side of the pond. They are undoubtedly superior to central european tyres on packed snow and ice, but worse concerning auqaplaning and slush. I have been using Michelin Alpin tyres - from Alpin over A2, A3 and now A4 - on my saabs since 2007, and cannot complain.
Nice handling when dry, not as squishy as most other winter tyres, not stellar, but sufficient grip on "white" roads (my parents live in Sweden in a "saltfria kommun", salt-free municipality, so christmas holydays is always on snow and ice), very nice in slush, and they tend to last forever. Our family (my father has been driving Michelin for ages) always gets 50.000 to 60.000km on front wheel drive cars (VW Passat typ 32b, Peugeot 405, Peugeot Partner, Nissan Micra, and several Saab 90, 900 and 9000), when every other tyre I have tried lasted 30000 to 35000km at most.
My current Michelin A4 have 7mm left after 18000km on the front wheels (until then unrotated). They started somewhat around 8,5mm, if I recall correctly.
I shall never, ever buy a Continental again. Yes, they tend to win every test they enter. And they are, admittedly, great when new. But they do not last well. I once had a set of Conti TS 790 or 810 on my first saab. First winter was absolutely great, second was horrible. I also had to dispose of two sets of Conti Eco Contact summer tyres after just 20.000km with nearly 2/3 of the thread remaining. They, too, were absolutely great when new. Then, all of a sudden, they stopped working... suddenly, even my old mercedes w123 diesel's asthmatic 88 horsepower (in a two-ton car) would be enough to get the car powersliding on wet and dry tarmac alike. Needless to say stopping distance or cornering ability were likewise affected. My guess is that they use two differend compunds, a soft one on the surface for winning tests, and then something rock hard underneath for thread life. Clearly optmised for test performance at the expense of customer benefit.
I'm tempted to call them the VW of the rubber industry. Never again!
All my Michelin tyres, be it summer or winter, seem to start at about 90 or 95% of the Conti's performance, but not only do they last, they also keep performing. If you drive a lot and are willing to compromise a bit on "new" performnace, so that you do not end up with either bald or useless tyres in the middle of winter, they're probably your best option. And on a €/km base, by far the cheapest.
Note: all this applies to tyres up to and including the A4. I've not yet driven the A5, but if the tyre tests are to be trusted, Michelin seems to have given up a bit of dry performance and a lot of longevity for a tad better snow performance. I'm not really sure if I would want to buy that.
