'Goodfellas', while great, doesn't even come close to the greatness of the first two 'Godfather' flicks. Allow me to explain....
'The Godather' (and it's sequel) were more honest and intimate portrayals of what it was to be a powerful mafioso during the time when guys made careers out of it. It's power comes not from overtly flashy characters with dialogue that's intended to be catchy, but from a subtle approach in which pacing slowly reveals characters while properly building tension towards it's potent crescendos.
On the other hand, 'Goodfellas' is a much more stylized and over-the-top portrayal of what it was like to be a made guy during the collapse of organized crime due in large part to disloyalty, paranoia, and drug use. It's characters are flashier and more outwardly entertaining, it's dialogue is written in a way that's intended to be catchy and quotable, it has a narrating character to guide you through the story by hand so that it never seems dull, it intentionally leaves out certain events that happened while making up others that never did in order to be more compelling to a viewing audience.
It's power lies in a more modern cinematic approach of basically bombarding you with flashy visuals, catchy dialogue, and over the top depictions of violence.
Don't get me wrong : I f*cking love 'Goodfellas' just like everybody else, I just think that cinematically 'The Godfather' (and it's sequel) is definitely more of a masterpiece. The fact that it's universally loved as widely as it's critically acclaimed almost 40 years later is a testament to it's true worth.
And it achieved that recognition without any of the pomp and circumstance that 'Goodfellas' had.