When I was a young man, I took a portion of my signing bonus upon the completion of my studies and purchased a Saturn Sky Redline. That car had a 2.0L turbo, not unlike the 328i. GM subsequently released a factory-approved software modification ("mod", if you will) which boosted the hp/tq to 290/340 - the car still had unbelievable fuel economy (2.0L, less than 3,000 lbs), handled beautifully (very little mass at the front), and was, overall, pure driving pleasure.
What I'm driving at is that with increasingly stringent legislation and increasingly unfavourable supply/demand fundamentals for fossil fuels, the 2.0t represents the engine (and thought process) of the future. I think the 328i is logically one of the best mid-size saloons of a sporting nature out there today - and, I can tell you that this is coming from someone who has had an anti-BMW bias for his whole life (some of the BMW clientele I've come across has proven to be most unfortunate, for humanity in general... you know, the guy with the wide open shirt and gold chain racing to the bumper of the car in front of him... stomping on the brakes... weaving like an idiot in traffic... and on it goes...).
What is undeniable, though, is the charm of the 3.0t. I've driven both cars, and while the performance difference between them is perhaps negligible in a practical "real world" scenario - within a few tenths here/there - the feel is totally different. The sound of the three-litre signs the beautiful tune of a bygone era. The feel is intangible, but it's definitely a cut above. If you don't have to make the logical choice, go for the 335i - the days of this old-school driving enjoyment are numbered.
If I were to "value" the cars on measurable quantities (including applicable insurance, consumption, payments) per tangible unit of performance, I think the 328i is indisputably best. However, if I didn't have to make the logical choice based on my current situation (wife will be driving the car to commute, impossible for me to get any time to myself to just have a Sunday morning blast through the countryside), I would certainly be in the 335i in a heartbeat.
It's a simple choice - one is the logical choice, and the other is the emotional choice. Whichever choice you've made, congratulations on making the right one. I think our friends in Europe would most certainly go for the 328i ninety-nine times out of a hundred - there's always one crazy bastard who just can't help himself (we salute you!).
Ah, what a timeless pub debate ...