When I was last in the market and ended up buying my Impreza, I cross-shopped the Focus. Nice car overall, but I didn't like the center stack's layout, I didn't trust the reliability, and I couldn't help but feel that the car would depreciate rapidly.
The GTI has below-average reliability and almost certainly costs more than $21.5k if purchased new, so that's out of the question (although I acknowledge that, when operating properly, the GTI is a great car). I suspect that a gasser Golf would meet the price constraints, but again, it's a VW, so forget about it.
A Mustang doesn't have the cargo and rear seat capacity of my Impreza, and rear wheel drive isn't what I want living in NYS, so that's not a contender.
Other than the GTR, I'm not a huge Nissan fan.
The current Mazda3 was a consideration, but it's getting old and I don't like the front end. The next-gen Mazda3 will probably be great, but that wasn't an option a year ago when I was in the market.