i'd say right now the ///MZ4 coupe, almighty straight six, perfect handling, long bonnet, sexy design, minialist interior, and the choiceof a 6 speed manual.
this is as pure BMW as possible without going overboard as in the CSL cases.
it is still a relatively attainable car, cheapo for what it gives, and provides all creature comforts one expects without effecting the driving caracteristics
as such, the ///MZ4 coupe offers a very much rounded package that if in full compliance with BMW philosophy
all other things being equal, the coming M3 will also comply with all i stated above.
remember, the epitome of what embodies BMW"ness" must be a real great package but must also be something we can all aspire too.
i would love to get my hands on a coming M6 CSL, but chances are i would hit 6 feet under before i can, which is true of a huge percentage of the motoring masses
for now i would say specifically the Z4 coupe (in M iteration)
the 3er also is just as BMW, but its ubiquity, and its broad range of engines, and the fact that is becoming more and more upmarket means that it has lost a bit of "special" edge that it used to enjoy in previous iterations, without losing any particular attractiveness
if we want to talk about specifics and not broad packages, the 7er is embodying the new BMW path most, on design and tech terms, and it seems it will be the model per se for all future showcases, and it deserves a great laudation since it is a huge risk to mess up a flagship model given all its implication on the lower mass market ranges
so to sum up
1-Z4 coupe (M)
2-7er