I had a 2009 Subaru Legacy GT 5 speed, not a WRX.
Going from that car to a Challenger is a huge upgrade. It's more fun to drive with the torquey V8, and makes you feel like king of the road. It's bigger, and badder in every way. Nothing like sliding sideways in turns as you stab the throttle.
You don't miss the boxer rumble when you get 4 more cylinders and a deeper, ballsy sound. The V8 Hemi is something to hear, especially if you have an aftermarket exhaust.
The Challenger is 10xs more comfortable than the Legacy, and now have tons more room when I drive. I always felt uncomfortable in the Legacy for long drives. The Challenger and the word cruise, mix together like chocolate and peanut butter. This car was made for cruising.
Looks is not even a competition, the Challenger owns any Subaru IMO.
Interior is nicer on the Subaru. Just brighter, and looks fancier.
The AWD system sure is nice if you drive during the winter, however I manage find with my Challenger with 18" wheels and Blizzaks.
I do not miss my Subaru ONE BIT.