WHICH ONE IS THE BEST? i heard that theyr all good but i heard that the mercedes has more problems out of the three. Is this true??

You heard correct. Go for the Lexus. Hondas are good when new but don't age gracefully, the original M class has been called "chronically unreliable" and "shoddily built" though they have fixed some of the problems with the ML. The Lexus is basically a Toyota and they have the quality and reliability that M-B had from the 50s through to the 80s.