1. Last Crusade
2. Raiders
3. Crystal Skulls
4. Temple of Doom
The hate for Crystal Skulls makes me sad. There's always been a big supernatural element to Indiana Jones stories, and I have a much easier time accepting aliens than I do weirdo heart-pulling voodoo something-or-other cult things. Temple of Doom was okay, but the somber village scenes were awkward, Willie was annoying as shit, and I felt like the dialogue is hands-down the worst of any Indy movie. The only thing I remember disliking about Crystal Skulls was the nuking of the fridge thing, which if you ask me is only marginally more absurd than Indy, Willie, and Short Round surviving that plane crash by riding an inflatable raft.
My theory is that people built up their expectations for Crystal Skulls too much, and when it didn't turn out to be similar enough to their nostalgic favorites, they were disappointed. I think it's a perfectly fine movie. Not Indy's best, but still way better than the Temple of Doom.