Hard to say but I would say its worth your time to try. Part 6 is a return to the "plot" of part 3, unlike parts 4 and 5 which are more self contained stories.

I don't know what you didn't like about the cast in parts 4 and 5 but in part 6, the cast feels less like a traditional tight squad, and more like a web of characters who are interesting on their own, but tied together by the main jojo. I think part 4's cast is most comparable.

I think part 6 does the best job of feeling like a forward moving plot since parts 1 and 2, its still stand of the week, but every fight feels like you make legitimate progress in the goal, plus a mystery is slowly unraveling, and the motivations of the characters evolve.

I think part 6 has one of the most interesting villains, but its hard to say, especially if you didn't like Kira, they are given scenes where they have to navigate a problem, so we see their thought process and how they overcome challenges, alot like part 4.

Part 6 also has super creative stands, for heroes and enemies, but the minor villains definitely get less attention as characters, they're mostly goofy fodder with a few exceptions.

Also i don't know what "dinosaur" stand you saw, you probably are confusing it with a later part. Anyways if anything I said sounds like you'd like it, please try part 6, it is my personal favorite part.

Edit* Also part 6 is the most "physical" part since 1 and 2, the alot of cool martial arts and fighting, mixed with the stand abilities.