>>712668198
A loaded question with an impossible answer. Fans will generally say Classic 2 or 3 and X1 or 4, but there's so many games it's impossible to say one is inherently the best altogether of all of them. So many minute differences, notable additions, big shakeups. I don't like Mega Man 2 much myself but enjoy 6 a lot despite some people seriously treating it like a black sheep, for example.

For an inverse answer to your question, never let anyone tell you Mega Man 7 was bad.