fall for "Kodachrome 64 is the best" as it simply isn't true anymore
If you're a hardcore slide junkie, in my eyes it certainly is still true, very true.
Sure, there are films out there with finer grain but nothing beats the "resale" value of a perect Kody ramp slide, period. No question about it. Of course, if you're not into "it", then I'd recommend Fuji Provia 100F or any of the others suggested above. Heck, just go digital