My ranking:

1. Raiders of the Lost Ark (I also consider this the greatest adventure film ever made)

2. Indiana Jones and the Last Crusade

3. Indiana Jones and the Temple of Doom (a close call with Last Crusade, which I love just a little bit more)

=4. Indiana Jones and the Kingdom of the Crystal Skull/Indiana Jones and the Dial of Destiny (these are both lesser beasts, though not as bad as some make out, and I consider them about as good as each other).

For more detail:

Raiders of the Lost Ark: https://medium.com/cinemania/raiders-of-the-lost-ark-40-years-on-ac595ebb7a1a

Temple of Doom: https://fanfare.pub/indiana-jones-and-the-temple-of-doom-racist-sexist-too-violent-6d873271037

Last Crusade: https://fanfare.pub/indiana-jones-and-the-last-crusade-where-it-should-have-ended-f7830f4eb905

Dial of Destiny: https://medium.com/simon-dillon-cinema/film-review-indiana-jones-and-the-dial-of-destiny-ac826dbfbd8

(I haven't written a piece on Kingdom of the Crystal Skull on Medium.) :)