Ektachrome EPR64 that expired in 1981 & 1984...
May sound odd, and don't look for it on B&H, but I bought a bunch of this a year or so ago from a guy who apparently had a photographer relative who didn't rotate the film stock in the freezer... got two batches of 35mm, one that expired in June'81, another that expired in March '84. They'd been frozen right along (decades!). Also got a few rolls of 120 that expired in '94, which I haven't used enough of yet to see the color extent.
I'm shooting it as ASA80. The palette is great - especially the browns and other 'early spring' colors. The blues are also great, and purples. Maybe I can get some scanned and posted at some point. I've been using expired film since I was a student in the early '90s, and this is by far the most fantastic and unusual emulsion I've found. Nothing unrealistic or color shifted or weird, just different and beautiful. Almost magic, really. I won't use it for everything (not so good for the interior Alaska winter scenes of white, gray, and gray-green), but looking forward to spring colors in the Upper Peninsula (bike trip in May) to use some more!
For new film I like KR64 (and KM25, which is still 'new', relatively, for me).