As three of the four Pokemon that evolve by Dusk Stone are Ghost-type, I feel something ghosty would work best. There are two enchantments I feel would work: the Soul Speed enchantment introduced in 1.16 or the Swift Sneak enchantment introduced in 1.19.
Soul Speed makes sense because ghosts are souls separated from the body, there are a lot of Ghost-types in the Nether, and the Soul Speed enchantment makes little ghost particles come out of the soul sand or soul soil you walk on. Soul Speed III on Dusk Stone boots would also allow you to go zoom in Soul Sand Valley due to all Evolution Stone boots also granting +50% speed.
Swift Sneak would make sense because Ghost-types tend to be sneaky, the Dusk Stone tools grant invisibility which is also connected to stealth, and the Swift Sneak enchantment is found in ancient cities which are ominous places. Swift Sneak III would also help with Nether exploration since Swift Sneak III combined with the 50% speed boost means you can sneak 12.5% faster with the boots than walk without the boots while still avoiding falling into lava.
I don't know which of the two would be considered better (I'd personally prefer Soul Speed though), but either of these would be an upgrade from the set simply granting Saturation.