I grind to the point (in any game) where I slightly surpass the enemy, but not by much. That way I feel accomplished, I can feel my characters development, and it's not too easy.

I know some people who just max out their characters and it's like "I could just 1 hit the last boss". Why? It's supposed to be challenging. You're supposed to be able to do a bit more thinking than Attack. Done. I can see why they do it, and that's great for them, but it just isn't for me. I like to watch and feel my characters develop overtime. I like them to all have strengths and weaknesses. I like the boss battles to be more challenging because it's like, it was hard, and I still did it. It took more than an attack. It took strategy. It took some thought.

But I guess its just a matter of opinion, really.