I generally agree with you, but I am not so sure about that last statement ('Lexus is better, hands down')? I think equal footing is closer to the truth. Both build beautiful, well-engineered cars. However, after doing so for more than 100 years, I think Mercedes deserves some extra credit.
For years, people have grouped Porsche & Rolex together as being similar brands in their respective markets. But, having owned both Porsches & Mercedes (& Rolexes), I think the 3-pointed star & coronet are a much more accurate match-up, in terms of quality, longevity, the scale of their product offerings & technical innovation. And, more importantly, each icon - 3-pointed star & coronet - is a universally recognized symbol of quality, refinement & status. You could go into the darkest jungles of Africa & you will find that people know what those icons stand for.