I broke up this franchise into 2 possibly 3 parts as not all movies are the same and most are different in terms of scenario
1, 2 and 5 are of course classic status
but at the time 1 and 2 came out nobody had no idea that it would turn into the franchise we saw today. I mean 2 drops and there's no Vin but it was still great and showed PW could carry this film, then tokyo drift comes out and while I saw it in theaters I figured after Tokyo drift this franchise would go into American Pie status with straight to home flicks. Then 4 came out with both Vin and PW and it was the start of a new trilogy(to me at least)
I think it's unfair to rank the classic films up against the newer films simply because if there's one franchise that has evolved to survive, plot,characters amount of CGI used and ridiculousness, it's this franchise and Even more so than something well established like Star Wars, because well they still deal with the force and jedi and the dark side and such. Fast really doesn't have it's original element or it's not as prominent as it once was.
It all comes down to opinion but there's no way I can rank anything above 1 or 2, especially 2 because we got Roman, and Tej, not only that but the film was a great character development piece for Brian in terms that now that Dom is gone what does he do now, go back to being a cop or keep down the path he's on. That dynamic played well into the 4th movie as when Dom returns they're at odds again
just my 2 cents