As a Morgan collector mainly, I'd probably go with the notorious 1888-O VAM 1B “Scarface” Morgan Dollar. The badass looking lady liberty results from a severely cracked die (the later stages of striking = more prominent effect). Note: PCGS MS62 example from their site, not from my collection (I wish!). Ron Guth excerpt from PCGS Coinfacts: Curious to hear others' favorites!
I guess it's the recently discovered die error involving the 1922-S Saint-Gaudens that Roger Burdette found: https://www.coinworld.com/news/prec...-eagle-variety-has-file-marks-on-obverse.html
I love the Shield Nickel / 2 Cent Piece . I have the Small Motto and Large Motto 1864's. I also have 4 out of 6 so far of the 1868 shield nickel varieties . Here's a couple Pics. 1868 FS-904 /( 1864 2 cent sm. motto . ( DUG ) )
My favorite errors now... doubled die... and Canada 25 cents struck on 1 cent planchet... and 1 more doubled die... and varieties... 1984 doubled die doubled ear variety...
Keeping it to what is in my collection, ERROR a Canadian cent counter collar clash VARIETY 1883 CC Morgan VAM 5 with bar under second 8 and die abrasion between the date and the denticles
Sorry. The 2nd and 3rd pics are not mine. But the slab coin is mine. I can not find the full image of my coin. ugh really sorry.