This seems like an issue where the fanbase is always interestingly split. AMC showed all 3 movies on Friday night and these are my observations:
Back to the Future 1 - Never really cared for the setting, and all the corny jokes Marty makes about what is to come. Biff is great, and Marty/Doc have wonderful chemistry together. Crispin Glover does a superb job too. It's a little weird how casual the film is about rape and incest, and it strikes me as really disturbing that Marty's plan was to somehow molest his mother so that his dad could come to her rescue. I suppose that makes it almost more funny that his mom is totally down for some in-car sexual hijinks and it requires the actual intervention of Biff to pull everything off. It's great as a standalone film.
Back to the Future 2 - I loved to futuristic 2015 sequences of this film when I was young, but now they just seem really off-putting. All the product placement is irritating and ruins immersion. While I can't fault any creator for having an incorrect vision of the future, some of the predictions are outright dumb. People will wear 2 ties at the office instead of 1! Hoverboards are still cool though. The dystopian Trump/Bifff 1985 sequence is largely solid up until the point where Biff just decides to murder Marty. It's a little weird how the antagonist in this series slowly goes from lunkhead bully to rapist to murderer. Where this film really shines though is in the 1955 sequence, and we revisit the events of the first film. Everything fits in perfectly and we are treated to a new narrative that expands on what we saw and enjoyed in the first film. All this is just so masterfully done I can't help but marvel at it.
Back to the Future 3 - I think it is hard to judge this film on its own merits. A lot of the gimmicks of the series are really starting to wear thin and be transparent at this point. Marty looking at some fading photograph to judge his progress is tiresome. Actors playing their own ancestors or distant offspring is tiresome. The filmmakers seemed so in love with this gimmick that I imagine if they had had the technology to do so, Crispin Glover would not have been in BttF1 and Michael J. Fox would have just played his own father. The movie is filled with corny ironic jokes like "You should be thinking about your future". The love interest plotline for Doc Brown is kind of annoying and hollow. If I was a bigger fan of Westerns maybe I'd get more of a kick out of this movie, but as is it's hard for me to have fun. I don't like that Marty's character arc is basically "He learns not to let people provoke him by saying he's a chicken." More frustratingly, Doc's arc seems to be "He goes from caring about the preservation of the time-space continuum to not really giving a fuck about anything he does when time-travelling." Not a bad movie overall, but viewing it in the context of its predecessors does not make it look good.
So in conclusion, I would probably have to pick BttF2 as the best film, but with the huge caveat that all the 2015 stuff is bad and should probably be skipped upon rewatching.
Back to the Future 1 - Never really cared for the setting, and all the corny jokes Marty makes about what is to come. Biff is great, and Marty/Doc have wonderful chemistry together. Crispin Glover does a superb job too. It's a little weird how casual the film is about rape and incest, and it strikes me as really disturbing that Marty's plan was to somehow molest his mother so that his dad could come to her rescue. I suppose that makes it almost more funny that his mom is totally down for some in-car sexual hijinks and it requires the actual intervention of Biff to pull everything off. It's great as a standalone film.
Back to the Future 2 - I loved to futuristic 2015 sequences of this film when I was young, but now they just seem really off-putting. All the product placement is irritating and ruins immersion. While I can't fault any creator for having an incorrect vision of the future, some of the predictions are outright dumb. People will wear 2 ties at the office instead of 1! Hoverboards are still cool though. The dystopian Trump/Bifff 1985 sequence is largely solid up until the point where Biff just decides to murder Marty. It's a little weird how the antagonist in this series slowly goes from lunkhead bully to rapist to murderer. Where this film really shines though is in the 1955 sequence, and we revisit the events of the first film. Everything fits in perfectly and we are treated to a new narrative that expands on what we saw and enjoyed in the first film. All this is just so masterfully done I can't help but marvel at it.
Back to the Future 3 - I think it is hard to judge this film on its own merits. A lot of the gimmicks of the series are really starting to wear thin and be transparent at this point. Marty looking at some fading photograph to judge his progress is tiresome. Actors playing their own ancestors or distant offspring is tiresome. The filmmakers seemed so in love with this gimmick that I imagine if they had had the technology to do so, Crispin Glover would not have been in BttF1 and Michael J. Fox would have just played his own father. The movie is filled with corny ironic jokes like "You should be thinking about your future". The love interest plotline for Doc Brown is kind of annoying and hollow. If I was a bigger fan of Westerns maybe I'd get more of a kick out of this movie, but as is it's hard for me to have fun. I don't like that Marty's character arc is basically "He learns not to let people provoke him by saying he's a chicken." More frustratingly, Doc's arc seems to be "He goes from caring about the preservation of the time-space continuum to not really giving a fuck about anything he does when time-travelling." Not a bad movie overall, but viewing it in the context of its predecessors does not make it look good.
So in conclusion, I would probably have to pick BttF2 as the best film, but with the huge caveat that all the 2015 stuff is bad and should probably be skipped upon rewatching.