i think for me it has to be a balance (yes, i know thats a cop out).
for example, when i bought my current car, i bought it over a couple of 330i's and 330d's simply because as an ex BMW show car, the 325i had idrive, premium stereo, sport pack, auto wipers etc etc. Its a good enough engine that it works in balance with the features it had.
Would I have chosen a 320i with the same spec? no, probably not. Would I have chosen a 330i without some of the toys, possibly, its hard to say.