Is Acura or Mercedes-Benz better?

My mom is considering buying a luxury car in a few years to replace her Mercury.
After reliability issues with American cars, my mom is disappointed with the reliability of them. My dad made the switch to Hyundai and we've had very good experience with them.
I know Acura is made by Honda, and Honda is said to be even better than Hyundai. But, while Mercedes-Benz makes cars of good quality, I've heard their reliability isn't as good as Honda or Hyundai (or Mazda, my family knows a lot about Mazda's reliability as my dad had considered buying a Mazda6). If Mercedes-Benz and the other German car brands no longer make reliable cars, why is this?

Mercedes hasn't made anything reliable since the 80s. The built to cost transition of the 90s really gutted Mercedes vehicles. As for Audio and VW, they've never built anything reliable since the VW Beetle. Only BMW seems to have held on, though with all the new electronics, it too is going downhill with the other German brands. As for Acura, every one of its models has a Honda counterpart. For example, a TL is just a glorified Accord. Acura sadly hasn't built anything that appeals to your emotions since the Integra. Try optioning up a Japanese economy car before considering a Japanese luxury car to save on maintenance costs.