Honestly, titles like 'Solo Leveling' and 'Omniscient Reader's Viewpoint' are everywhere online, but that's mostly webcomic talk bleeding over. The pure novel side feels a bit different, at least in my circles. Stuff like 'Mushoku Tensei' still has this massive, dedicated following because the novel really is the definitive version—the anime can't cover all the inner monologue and world-building. 'That Time I Got Reincarnated as a Slime' also seems evergreen; people love the combination of nation-building and chill vibes.
Then there's newer or niche hits. 'Ascendance of a Bookworm' doesn't have the flashy battles, but its fanbase is fiercely loyal for the meticulous crafting and economic detail. 'Eighty-Six' gets a ton of praise for its serious mecha-war drama and emotional payoff. And I wouldn't sleep on 'The Apothecary Diaries' either—the mystery and historical setting hooked so many readers who don't usually go for isekai.
For a weird take, I think popularity is shifting towards stories with a strong, singular voice from the protagonist's POV, like in 'ORV', rather than just wish-fulfillment power fantasies.