Never liked Part 3, a big fall in quality after the first 2

Disagree. The first 1 needed no sequels.

part 2 have more edge to it. having edge give film substance.

part 3 is more light and easy, but no edge. but focus on doc and clara not that interest. but still decent sequel i think.

Funny, I consider Part II the worst of the trilogy.

While still enjoyable, it's definitely the messiest and most dated of the 3.
Sure, it toys with some unique ideas, but mostly just relies on silly gimmicks and direct references to the original film to keep it afloat, rather than focus on characters and story.
The plot holes are beyond abundant, apparent, and difficult to ignore. The tone is all over the place. Then of course there's the depiction of the future (2015) in the first act, which over time has become less awe-inspiring (the obvious intention) and more outright ugly and garish. This part may come off as nit-picky, but it's really not helped that this vision of the future turned out to be a far cry from the 2015 we'd eventually get - a contrast to the original films' timelessness.

Part III is a more completed movie with focus on both plot and characters, and more consistency with the plot. Nods to the previous movies are present, but not to the point of overreliance.

I know a lot of people don't care for this movie, but I just adore the love story between Doc and Clara.

The original is one of my favorite theater experiences of all time. I didn’t really care for the second one. I enjoyed the third but not to the level of the first.

Like Raiders of the Lost Ark, I like BTTF 1 and 3 and don't care nearly as much for 2.

Gahh, I loved all of them. The second and third are very flawed, but they're still great movies with lots of fun.

When I was younger I always thought 2 was the best...now in retrospect 1 is obviously the best and 3 is a better movie than 2.