I can tell you the Hakka II is the most incredible winter tire I've had on any vehicle. I've never owned a set of Blizzaks but I hear and read they are extremely good too (though obviously not an all season).
The manager at a local STS Tire Shop by me swears the WR Nokian all season tire will perform as good as the Blizzak on ice and snow while still being a true 4 season tire and go 40,000 miles if not longer. No doubt, a very tall task but he has given me no reason to doubt his word. He claims to have witnessed it first hand at a Nokian test facility which was basically a frozen lake bed. Two identical cars, one with a set of Blizzaks and the other with the WR all season and the Nokian a/s equalled the Bridgestone in accleration and stopping and outperformed the Bridgestone in cornering/lateral grip. If it really is true, simply amazing!
They are pricey though but if it eliminates having to buy dedicated winter tires they would be cost efficient.
Right now I'm torn between spending the cashola on a set of RSI (rain,snow,ice) Nokians for my Mazda or going with Blizzaks. A $240.00 difference separates the Bridgestones and Nokians....much more than just pocket change!