I think what everyone's problem with part 2 and 3 (seeing as how everyone mainly loved part 1 the best) was how drastically they changed it. In part 1 we get this down to earth pirates film with great new characters we don't see too often. And then in part 2 we get way too much comedy, an unneccessary cannibal island sequence (though it did give Sparrow a reason for having to look for a brand new crew when Day Jones needed the 99 souls) and a huge step up from the first film (now we've got supernatural sea people, a guy with a squid for a head, and a gigantic sea monster).
While none of that bothered me much, I still enjoyed the film. People complain about how hard it was to follow and stuff like that and how the plot kept changing...well that didn't bother me much at all. IMO it made me like it more because nothing went as planned. Too many times in movies the heroes plans always go according to plan, but in this one every original plan had to be improvised.
Part 3 started off good, but then bored me once they reached the Locker. I think the movie could've done without the hallucination scenes. They just seemed really unneccessary, or they could've at least made them less.....Looney Tunesy. Davy Jones was down graded heavily (IMO) from this completely badass villain who almost outshined Barbossa, into this complete wimp (they really did it for me when they had Jones standing in the bucket of water.....and I just CRINGED when he did the Eastwood brow thing).
Cutler Beckett remained the same, and I hated the whole Calypso becoming the 50 ft woman thing. They could've done something a bit more.....better. I loved the backstabbing going on. People may complain about that the most, but I just loved it. It really shows that they must be quiet the team if they can backstab and trade each other's lives, and then go right back to having their backs in a hot second. I liked how even though Jack killed Barbossa, Barbossa didn't take up half the movie holding any grudges. Still, they could've toned down the comedy a bit, but other than that (like the rest) the maelstrom scene did it for me. One of the greatest things I've seen.
So yeah, I can see why everyone hails COTBP as the best one because it wasn't so over the top and the plot was much easier to follow, but really I like them all. I just hope Part 4 (hopefully we get a part 4) will kinda go back to those roots of part 1, seeing as how we have no more Davy Jones fish crew. The comedy can stay, just tone it down, and make Jack more like the Jack from part 1 (if that makes any sense).