i just traded my 09 si for an 11 wrx and if i had to pick a between the two based soley on comfort i'd have to go with the si. si is more ergonomic, has much more interior room way better stereo with a bit better functionality. when you sit in the civic you have a much better view of the outside world the dash is low so your vantage point is better. that being said the wrx has a better build quality i have less rattles with the wrx you're already turbo with the wrx and it makes power differently than the civic, as far as winter goes i live in mass and while i can drive a fwd vehicle in the snow there is no real comparison even with summer tires on the awd wrx is far superior in snow crappy weather. basically there's something to be said for both they are both good cars and are different and i have not driven the newer si but personally i feel honda has and is half assing with the 2.4l engine. i have done lots of with b and k series engines and the 2.4 is really a torque motor and honda's are hp derived motor so the 2.0l is way better from my experience
if your lookin for interior comfort based on the older versions i'd say honda, if youre looking for a better build quality wrx but they are both good cars but they're also just two different cars so it is hard to compare, also the wrx has a 15.4 gallon gas tank while the si has a 12 gallon tank, at least the 09 si anyway. the 12 si is supposed to have a much better transmission than prior years, they are known to have weak tranny's from 06, the wrx has a decent tranny as long as youre not beating on it with launches and slamming gears but remember awd feels the beating more than fwd because it goes to the drive train while the fwd will let the power just spin the tires. both good cars take your time drive both more than once and take your time making up your mind and if you have any question p.m. and i'll try to give my best opinion.