I'm a VW/ Audi freak but I'd also consider the 335i coupe. If you had to have all wheel drive, there's the ix. What about the 135i? That's stupid fast although it's a bit on the naked rosie o'donnel ugly side.
Here's why I was yapping about BMWs: http://www.advantagecertified.com/inventory/series.php?series_id=1 Bang for the buck used. They also have some Audis but no A5s.
I did give the 335xi a thought. I figure it would be the closest choice to the STI. I'm just not crazy about the looks. 1-series is out because it's rear wheel.