Second Best Sequel? What could have been better?

Rating: 10/10 (24 December 2004)

I remember seeing the Godfather, Parts I & II back in the late 70s. I haven't seen since, much less before, any 2-part cinema production that produced a storyline so well enmeshed, that they both could have been just called "The Godfather".
My question is, according to a comment I read on the website for the movie, it is only the second best sequel ever made. What was better? In my 58 years of watching movies, I haven't seen anything else to even come close. I find it hard to believe that anyone else might have a different opinion. Of course, I'm not an expert at these things. But then, I wonder if the comments made about it being "second best" were the comments of an expert, seeing as I have only heard it described by the critics as the best sequel ever, to which I readily agree.