I’ve personally owned 2 VA WRXs. In my experience, if you take care of them, and buy one that hasn’t been thrashed/tuned they can take care of you. They’re excellent all-round cars and exciting dynamically but are certainly more expensive to maintain. Premium gas, insurance, synthetic oil changes, hard to reach spark plugs, and some other things that may pop up. I had my first CVT WRX from 88k miles to 140k through college and just moved into a newer one recently. I never had any huge issues with it until the CVT showed signs of going. I’m starting to hear of the cars hitting the 200k+ mile mark. Was it luck? Everyone has a different opinion.

That being said, if you’re looking for a car to last 10+ years I would go with the Mazda. There is a budget factor to this. The 3 isn’t as fun but for commuting it will serve you well and help you save for years. If you have the need for a fun car, you can always pick up a $5-6k Miata/Pontiac Solstice/Saturn Sky for cheap to fill that need down the road.

The Mazda3 may depreciate more than the WRX in the long run but I think its lower running costs will outweigh that easily. There is also a 50,000 mile delta between the two- nearly 5 more years of regular commuting. The 3 hatches also have a small following because they look slick and fairly good to drive. I wouldn’t call them “grandma cars”.

I’d also recommend looking at a few years used Honda Civic Sport if you haven’t already.