There are a lot of cars you can get for $27.5k and under. I don't think you can go wrong with any of the cars you have mentioned except for the passat because the other cars are a lot more sporty. I really like the a4 and g37, they both look great stock and even better with suspension and wheels. I would go for the a4 on coils, rotiforms, tune and BOOM! So sick.
I have a 3.6 4Motion CC as a second car. I don't drive it a lot, but I love it. Exhaust note and engine growl put the GTI to shame. Good power. You can get good highway mpg if you set the cruise and stay off the gas (28-29). Mixed I can get close to 25. If you like the go pedal it can get thirsty. The seats are crazy comfortable. The ride is great. My only real complaint is that the steering is pretty numb/light and doesn't have much feel, but that's pretty much it.
I'd go G37X. I realize that all the VW guys also always like Audi and then BMW, but IMHO, the G37 is the most bang for the buck on the market, and I personally think it's a got looking car. If I were buying a new $40K car, I would buy a G37S 6MT. Ricer? Whatev. It's a bad ass car.