Reddit mentions of Tales from Ovid: 24 Passages from the Metamorphoses

This is hard to answer for several reasons. It's an overly broad question, plus each people's sexual tastes differ (and so do their age, gender).

A safe answer would be to suggest any volume from the Mammoth Book of Erotica series (you can find paperback editions of each volume for a few books. The series editor Maxim Jakubowski has excellent but very dark tastes.

Pauline Reage, Anais Nin and Henry Miller are the obvious choices (and really, erotica literature went mainstream in the 1950s or 1960s with Grove Press, etc).

There are many types of subgenres: the dramatic, the picarasque, the cinematic, sci fi/fantasy, the amoral, the short stories, the humorous. Surprisingly, I don't think I've read many humorous erotic stories (oops, I forgot, Candy by Terry Southern, hilarious!)

Many highbrow conventional novels have major sex scenes, but they are not really considered erotica --- just books that have naughty parts. Kundera, Marquez, Duras, Jeffrey Eugenides, DH Lawrence, Erica Jong. A lot of the unrequited love/love triangle books have powerful passion in their scenes. So do the memoirs and tales of victimization and abuse. Really any great writer can write a scene of erotic seduction.

Let me do a shout out for Ovid -- who is the ultimate writer of erotic fiction. Check out Ted Hughes' translation of some of Ovid's stories in Metamorphosis Also check out Heroides -- love letters between Greek mythological characters.

Finally, you might enjoy this philosophic dialogue I stumbled upon recently about the nature of erotic fiction (semi-NSFW, though text-only)