So many come to mind, but a few scenarios just dominate the discussion spaces I'm in. The 'enemies to lovers' tension is huge—there's something about that hate-fueled, competitive energy turning into desperate, forbidden passion that hits every time. Think a political rival you have to publicly debate, but you're tearing each other's clothes off in a hidden office afterward.
Another massive one is the 'forced proximity' trope, especially in a survival or fake-dating setup. The 'only one bed' scenario is a classic for a reason; all that simmering awareness and accidental touching in a confined space builds anticipation like nothing else. It's less about the act itself and more about the breathless moment right before, when both characters finally stop fighting it.
The whole 'morning after' scene, where the dominant or colder character shows unexpected tenderness or vulnerability, also gets a lot of love. That moment of softness after the intensity changes the whole emotional dynamic.