I don't know much about american cars, agree 300 is a great car.
When I choose BMW initially was because I am thinking to buy a luxury car with sporty handling.
My short list include InfinityG35/37, AudiA4/6, C calss, BMW 328/335/528, thought about Acura but never drove one. Out of those, I dislike C class and infinity for the handling. Audi was allright. Not sure if my short list missed any good car in similiar venue.