Man, if you enjoyed 'Reincarnated With The Strongest System: Book 1', you're probably into those power-fantasy, system-based progression stories with a mix of isekai and RPG elements. One title that immediately comes to mind is 'The Beginning After The End' by TurtleMe. It’s got that reincarnation vibe paired with a protagonist who grows absurdly strong, but what sets it apart is the emotional depth and world-building. The MC, Arthur, starts as a baby with memories of his past life, and watching him navigate politics, war, and personal relationships while leveling up is just chef’s kiss.
Another solid pick is 'Solo Leveling'. While it’s not strictly an isekai, the system mechanics and the protagonist’s journey from weakest to unstoppable are super satisfying. The manhwa adaptation is gorgeous, but the light novel’s pacing and internal monologues add so much more nuance. And if you’re craving something lighter but equally addictive, 'So I’m a Spider, So What?' is hilarious and clever—imagine being reborn as a dungeon spider and grinding your way to godhood through sheer stubbornness.