I might be in the minority, but sometimes the classics do it best. 'Fingersmith' by Sarah Waters isn't purely an erotica novel, but the tension between Maud and Sue is so thick you could cut it with a knife. It's a slow, agonizing burn across 500 pages of Victorian scheming, and when it finally pays off, it feels earned and incredibly intense. I've read it three times and still notice new layers of their coded desire.
For something with more explicit, modern heat, 'Wrong Number, Right Woman' by Jae is a solid contemporary pick. The chemistry builds through texts and calls before they even meet, which I found surprisingly effective. The actual spicy scenes are well-written and feel integral to the relationship's progression, not just tacked on.
Honestly, a lot of the self-published stuff on platforms like Kindle Unlimited can be hit or miss, but I've found some real gems by searching for niche kinks. The writing quality varies wildly, though. Some authors nail the emotional vulnerability alongside the physical acts, while others just string together clichés.