Do you like tactical RPGs?
Maybe check out the Disgaea series.
They're not for everyone but the reincarnation/transmigration feature plays heavily in maxing out your characters and learning new skills or spells.
While the main story can be beat at regular levels, around 60-80, most of the post game requires you to be at level 9,999 with multiple reincarnation. (That was not a typo.) The stat caps are insane. Depending on the game your caps could be in the millions or billion range. You can also level up your weapons and armor. Not enough challenge? You could pass a Stronger Enemies Bill, where all enemies are increased by 20% with the max at 400%.
The Disgaea games do have stories but they don't take itself seriously. There's multiple endings, dark humor, and no fourth wall.
Mao (D3): Having Chapter 1 as the final chapter...
What an economical game!
Muhahahahah!
Sometimes it does get repetitive but it's addictive and a major time sink.
Plus there's exploding penguins.