The first Jurassic Park movie is all time one of the greatest films ever made with the special effects still holding up to this day. The 2nd film was still very enjoyable in my opinion but it was just a cookie cutter sequel not bad, not good. The 3rd film wasn’t great at all. But compared to the rest of the series the 3rd film is basically the godfather.
As another personal pick the 1st blade movie is a hood classic good. The other 2 not so much.
Alien 1 vs Alien 2 is such an interesting split. The first is so full of dread and so claustrophobic. The second is like an action horror movie. The vision of Ridley Scott and James Cameron couldn’t be more different but both are great movies.
I really don't know what went wrong so hard with Alien 4. On technical side it was amazing. Acting was great with so many stars. The plot was so bad tho, I still can't believe they greenlighted such a horrible writing.
Imo that's exactly why the Allen franchise is/was so great. Each movie was something different, with a different director.