I agree, Crystal Skull wasn't as bad as many make out, though I'm not a fan of LePuff. The atomic bomb test site scene was a lot of fun. That's my kind of town - populated only by mannequins.
IMHO, Temple of Doom was the worst of the bunch, for several reasons, including the juvenile gross-out gags at the royal dinner table, the depiction of Indy even temporarily showing fortitudinal weakness and allowing himself to be drugged & hypnotized by a bad guy, but mostly because of that shrill, whiny, shrieking KATE CAPSHAW. Short Round was a great sidekick, maybe they should have just skipped the romantic interest in that one.