I agree with what everyone has been posting. The number one thing to figure out is what you want out of your car. I have drove a 6 speed A4 quattro and an FR-S (Yes I know it's not a BRZ but it's pretty much the same).
The A4 is definitely a fun car to drive with its AWD and 2.0L turbo, but it doesn't feel like you are "driving a car". It feels like you are playing a video game, you can't feel the shift linkages going into any gears (But I do not know how the automatic trans reacts, maybe it's more fun). It's a fast car but, to me, I didn't feel connected to the car in any way. On top of that the maintenance prices are quite ridiculous for this car and idk how long these cars usually last.
The FR-S/BRZ is very good in the handling department, but to me it lacked the power. Don't get me wrong, for a car that only weighs about 2700 lbs, it accelerates pretty well but not as well as the 370Z. The transmission is not as rough as the 370Z and the Torsen LSD operates pretty well, but I liked the looks and power of the 370Z more. This car would probably be a little more DD friendly though, if that's what you are gonna use it for.
Like I said earlier, it depends on what you want from these cars as they are all in different classes. If you want that acceleration that would put you back in your seat and has 4 doors, the A4 or maybe a WRX/STI/EVO would suit you more. If you want that light and nimble sports car with back seats and better gas mileage, the FR-S/BRZ would be a better choice. If you want a car that's well rounded when it comes to power, handling, and looks, but you don't mind that it only has 2 seats then you might want to go with the 370Z.
The best way to determine what you want is to just test drive all of them. I hope this helps!