If you already have summers, don't buy all seasons for the winter. Buy winter performance tires. All seasons get stiff in cold weather. Their compounds have to handle HIGH temperatures as well as cold remember, so they handle worse in the cold than a winter performance tire. Not all tires made for winter are designed for just bad weather. There are lots of good winter performance tires that will trounce any all season when it's below freezing on a totally dry course.
TEMPERATURE determines tire compound remember. Best tire in the cold will be one designed for cold temperatures. If you handicap yourself by buying a tire that has to also handle heat, it will be much stiffer as temperatures drop.
I'd go with 225/40R18 personally. Though I wouldn't have chosen 18" wheels...
2015 STi: Still Stock
04 STi, 04 WRX: SOLD