Merc vs. BMW
there's not much comparison to be had. these companies have a totally different approach to car building. if i wanted luxury i'd get a Merc. since i want sport i've got a BMW. i might consider an AMG Merc over a BMW for sport but then i'm paying 50% more for a comparable car. so really i'm back to BMW for sport. Merc has an incredible racing heritage too and both companies make awesome cars but i feel like BMW has a more youthful spirit than Merc.
i agree with the person who said to get both!