subaru is nice for snow and all that, but they are kinda shitty, i test drove 4 wrx's when i was deciding between that and an s4. each one had one or more things wrong with it, on everyone atleast something on the inside was broken like the cupholder, one shook like crazy, mabye cause of allignment? and one was grinding in to two gears.
the good thing is that subaru's are cheap to fix.
i drove 3 s4's and none of them had any real problems, the biggest problem i found was the screen that displays your mpg and all that had lines going through it for some reason.
ive owned my s4 for 1 1/2 years and i had to get the tranny replaced, luckily it was because my sister drove it for 4 months and she beat the hell out of it. other than that there are no real problems.
the only bad thing is that audi's are expensive to fix(unless you do it yourself)
and for awd, subaru's awd is more electronic and less mechanical, so its easier to control but less capable. audi's is more mechanical and harder to control but more capable. so overall its pretty even, if your a really good driver, or into performance driving and all that an audi is probably better, if you just want to get through snow or whatever with little effort and could care less about performance subaru would be better.
if you want to spend around 10-15 get either an a4 (1.8t) or wrx. if you want to spend 16-25 get an s4 or sti.
and remember audis will always be alot nicer inside and all around quality will pretty much always be better, but that means you wont want to get it dirty when your skiing and that can suck.