The issue at hand is that these cars possess distinct characteristics, making the determination of which is superior purely a matter of subjective personal preference. To begin with, if you are enrolled in a work car scheme, the i4 would be significantly more affordable in this context, potentially resulting in a considerable reduction in cost. However, it should be noted that the i4 is essentially a standard 4 Series that excels in straight-line acceleration. On the other hand, the M3 offers an entirely different driving experience. Whether or not you desire that particular experience is a matter of personal preference. Personally, I would choose the i4 M50 over the M3 because I do not find much value in the additional capabilities offered by the M3, but your perspective may differ.