all comes down to what you want from the car, if you want to tune it then it's got to be turbo'd as the cost vs performance gain on a naturally aspirated engine can get ridiculous.
Audi TT can look like a hair dressers car BUT the right spec or exterior upgrades can easily change this, also the Audi TT is a nice place to be inside but not really any good if you want to carry more than 1 passenger.
Audi s3 is a very good all round car, plenty of tuning options, very practical and look nice but there's a lot of them around and most of them look the same, there easily blended in with other cars in traffic if you no what I mean.
BMW 335i is a beast of a car, quite rare In manual, never heard anything bad about the auto box in them but never heard anything good either. The one I drove ages ago felt quite stiff. Probably going to be dearer to insure than the above 2 as its rwd and also won't be as economical.