In my experience, all good tires are biased towards one condition. Most all-season tires are "jacks of all trades, masters of none". At best, they are mediocre in any given condition, but forget about spirited driving in the summer and getting around swiftly in the snow. Some of us call them "no-season" for a reason. The only advantage they may hold is the long thread life, but on the flip side, that means not as good of a grip.
If you want something that you can run year-round and perform well in snow, try all-weather tires. Nokian WRG3 is a good example of it. It's more biased towards winter driving, though, so the summer performance isn't that great.
If you have a garage, buy a set of steelies and run 2 sets of wheels.
What you want to look for in good snow tires is the snowflake symbol. M+S is shown to be worthless nowadays, seeing how some summer performance tires have it.
Like others have mentioned, good stories about all seasons doing great in the snow (try it with RWD) and I have similar experiences until 2001 when I moved into my current house. ALL of the yang I was telling friends about "all seasons are all you need if you have FWD and I live in Ohio" was null and void when I moved up the mile long 10% grade I live on now. All seasons are entirely inadequate.
We had our first snow yesterday. I just mounted up my steelies with Nokian Nordman 7 SUV on the Pacifica tonight and last night, I mounted up the alloys and Dunlop Wintersports on the Accord.
I had the Altimax Arctics put on the S60 (lease car, not buying wheels with an odd bolt pattern I'll never use on another car) today and one had a hole in the sidewall after only 1 season. I wonder if something is going on. I store them flat and stacked. Alloys/Wintersports for the Accord stacked 4 high and rimless Altimax stacked on the alloys 4 high. Same as the tire stores.
Last April when remounting the stock Volvo tires, 3/4 Continentals had sidewall blisters and I had to buy 4 new tires. They were stored the same way. Wal Mart wasn't pulling my leg. They circled the blisters and didn't charge me a dime for double the labor (mount the stock, discover blisters, re mount the snows) and they didn't try to sell me new tires. I've never had a problem with storing Ody, MDX, or Accord all season or snows the same way. I'm thinking about storing upright for this season. Lease is up in July. I'm also thinking of storing Pacifica tires upright which I've also seen at tire stores when stored on a rack. Funny, the only tire issues I've had are with mounting and dismounting and never with a wheel tire package.