Vanilla MC - it's okay, I guess? I liked the crafting/survival elements, was underwhelmed by the combat and exploration, and had little interest in building. Maybe I would have liked it more if I didn't play Terraria first.

Modpacks are another matter entirely. A near-endless source of entertainment that add much-needed complexity and fresh exploration. I've played them for longer than I'd like to admit and still do sometimes. (They can be a pain to get up and running, though.)