Roger Cole
Subscriber
Astia might be the closest. Though the palette of any E6 film isn't going to be a very close match to Kodachrome. You won't get the Kodachrome reds and you won't get the odd, sometimes pleasing and sometimes ghastly Caucasian skin tones that Kodachrome often gave either, especially with a warming filter as such skin tones tended to go cool. I have some slides of some people with ruddy complexions shot outdoors where Kodachrome really made them look better, and I also have some shot with electronic flash where they look like deathly pale ghosts.
Even so, Astia too has been discontinued, a huge pity because it was absolutely favorite E6 film. (Well and Provia 400X - they are so different and fit different needs.) You can still find some at times, and it should be fine if late production and cold stored, but it's a lot harder to find than Ektachrome (particularly the consumer Elitechrome) and apt to be more expensive when you do.
Even so, Astia too has been discontinued, a huge pity because it was absolutely favorite E6 film. (Well and Provia 400X - they are so different and fit different needs.) You can still find some at times, and it should be fine if late production and cold stored, but it's a lot harder to find than Ektachrome (particularly the consumer Elitechrome) and apt to be more expensive when you do.