Man, I love this question because my taste has honestly changed a lot over the years, and what I'd recommend now isn't the classic high-school AUs that used to dominate. That said, I do feel like a lot of the absolute top-tier Superbat fics have migrated off Wattpad to AO3. The platform's tagging system is just so much better for finding that specific dynamic you're craving, whether it's canon-adjacent or a wild AU. But if you're sticking to Wattpad, you gotta dig. One that still holds up for me is 'The Bat and the Sun' by BatShadows. It's a slower-burn, post-'Justice League' fic where Clark is grappling with the weight of being Earth's savior and Bruce is... well, being a paranoid disaster. The author nails Bruce's internal monologue—the guilt, the calculus, the sheer stubbornness—and Clark's warmth feels earned, not saccharine.
Another one I re-read recently is 'Of Kryptonite and Caffeine' which sounds silly but is actually a pretty grounded coffee shop AU. Bruce Wayne anonymously funds a small Metropolis coffee shop Clark works at, and they start this entirely anonymous pen-pal relationship through notes left on receipts. It's less about superheroics and more about two lonely people connecting, and the voice is so distinct. The side characters, like a very suspicious Alfred and a meddling Lois, are great. The pacing can drag a little in the middle, but the payoff is worth it. Honestly, my binge advice for Wattpad is to use the 'completed stories' filter religiously, sort by votes from maybe two years ago to find the hidden gems before the algorithm changed, and don't be afraid to ditch a story if the first few chapters feel too OOC. There's a lot of rough stuff, but the good ones really stick with you.
I'd be remiss if I didn't mention 'Red Sun, Black Knight'—a elseworlds-type story where Clark lands in Gotham instead of Kansas. It's a massive, sprawling thing with some truly epic world-building, though the grammar can be spotty in later chapters. The dynamic is flipped; Clark is the one shaped by Gotham's darkness, and Bruce is… honestly, kind of the hopeful one for once, which is a trip. It's not everyone's cup of tea, but for a long, immersive binge, it's weirdly compelling. Just go in knowing it's a commitment.