Just to let you know; this article is from 2011, so it's somewhat out of date. You could also try The Top Ten Dedicated Snow Tires For 2013.
Most dedicated snow tires nowadays are good enough that studded tires are not generally needed except in the absolute worst of winter conditions. If you do a lot of backcountry driving, or get deep snow that comes and stays for months, you might want to look into studded winter tires, but otherwise, studless tires are probably your best bet.
These five snow tires are the best studless tires available for the safest and most comfortable winter driving. Dedicated snow tires should be replaced with performance tires for summer driving, so thinking about a second set of rims for winter tires can often save on the long term expense of swapping tires back and forth on one set of rims.
A note on handling: If you read enough reviews or talk to enough customers, you will likely hear every winter tire ever made described as feeling “squishy” on dry roads. This is because compared to summer-only tires, all winter tires are in fact, “squishy” on dry roads, due to the flexibility of the rubber compound and the many other tradeoffs that winter tires must make. However, some winter tires are squishier than others and these degrees of squishiness are partly subjective and not always easily determined. I tend to give only secondary weight to dry-road handling characteristics unless they are rather pronounced, whether for the good, as in the Dunlop Graspics, or the not so good, as with the Blizzak WS-70’s.
The Graspic is very good in snow and handles quite well on cold dry pavement, but has some trouble with rain/ice/slush combinations. According to customers, they wear quite well, which is probably an effect of their dry road bias.
Bridgestone's WS-70 is certainly a huge improvement over their already-good WS-60, and may in fact have better performance on sheer ice than Michelin's X-Ice, which may or may not have to do with their top-secret rubber compound, which further may or may not contain metal particles. However, their top-secret compound wears quickly, and dry-road handling also suffers from excessive squishiness.
Some people disparage Continental for being essentially a second-tier tire maker. I like Continental for being the very best of the second tier, for making decent, durable tires for daily drivers at great prices. That's why I like seeing their excellent winter tire getting a lot of respect from testers, reviewers and customers. Conti's long relationship as a supplier of OEM tires for BMW makes these an especially good low-cost winter tire choice for BMW owners, as they often seem somewhat “dialed in” to handling the performance qualities of the car in winter conditions.
Michelin has made no secret of their desire to catch up to Nokian in the extreme winter tire market, and the Xi2 is their latest attempt to do so. Many testers and reviewers consider the Xi2 to be as good as Nokian's Hakkapeliitta, while coming in at a lower price. During the summer, I found this a good enough rationale to place the Xi2's at #1.
However, since then I've finally had a chance to drive the tires in the snow. Ultimately, in my opinion, the Xi2 is not quite as good a pure snow tire as the Nokian, but it is easily as close as anyone has yet come to it. Where the Xi2's really shine, however, is where they play to Michelin's strengths - performance, performance and performance. Driving Xi2's on clear or plowed winter roads is more fun than on any winter tires out there. Couple that with excellent snow and ice grip at a relatively low price and you have a great all-around winter tire that's all Michelin.
The Finnish tire company Nokian has a long history of making the best winter tires and driving technological innovation in the field. In fact, Nokian invented winter tires back in the 30's, and still holds more winter tire patents than all other tire companies combined. Nokian's long technological lead in areas like lateral grip and slushplaning resistance have made them leaders in the winter tire industry, and their commitment to non-petroleum oils and low rolling resistance are stances that the rest of the industry are just beginning to assimilate in a big way.
The nearly unpronounceable and unspellable Hakkapeliitta R (Hah-kuh-puh-LEE-tuh) is currently the centerpiece of those traditions. This year; the 75th anniversary of the Hakkapeliitta brand, Nokian has kept it's dominance alive, although by a very thin margin over Michelin's Xi2's. Although the Michelins are excellent tires, the Hakka R ekes out a victory almost solely on the basis of superior lateral grip, a Nokian specialty.
Full Disclosure: I am a big fan of Nokian tires, and I'm not all that subtle about it. Lest you think I shill for the company, I have been driving on their tires by choice for about ten years now. I've been recommending them to family, friends, customers, random people in parking lots, etc., for about that long as well. All I've ever received from Nokian is the keychain and coffee mug I get every year at the dinner and marketing presentation they put on for area tire people.
Avoid Like the Plague:
Hankook Icebear W300
I personally am not a fan of Hankook in general, but their winter tire appears to be particularly awful. Hankook's Icebear fails American snow and ice tests, and most European testers won't even try them. The Canadian Automobile Protection Association says they are “not optimized for snow and ice”, which I assume is a polite Canadian term for “Yuck!”
Firestone Winterforce M+S
This studdable SUV/light truck tire not only comes in at the bottom of its class while unstudded, but when the studded version was tested against three unstudded tires, the unstudded tires won handily. Firestone makes some very good tires, but this is not one of them.