Oh boy, now you're going to get the testimonials and stories!

IMO, you will do well with just about any quality fluid. Over the years, I've used a lot of different brands and never had a problem with any of them. Once you make sure you know the minimum DOT rating required (check owner's manual), you have tons of choices. I've settled on Valvoline Synthetic DOT 3/4 for my daily drivers. I also use ATE DOT4 racing fluid (about $11 a quart), and Ford (yes, Ford) Heavy Duty fluid based on recommendation from several racer buddies of mine who have used it for years. I avoid 'Super Tech', Wagner, and the other sundry DOT3 fluids stocked at the typical part chains. If you're really concerned, you can always go to your friendly MB dealer and buy their stuff.