First of all, of course, tread pattern. And not the fact that any of the proposed seller models of tires suitable for use suitable for your individual conditions.
It should be noted at once - ideal, fully suitable for you, most likely, simply do not exist in nature. Therefore, any choice of winter tyres will be to some extent a compromise.
To make an informed choice is important, but more important to understand the characteristics of the selected tires and be able to choose the style of riding in different conditions, depending on this. Security is primarily full control of the situation on the road and the maximum understanding of driver reaction of the vehicle to certain of its validity.
It was the bus to the greatest extent determines the length of the braking distance of the car - keep this in mind. Therefore, you should not rely on any particular tread pattern is much more important to wisely manage your cars.