Depends on the criteria.
I can't decide on a single game, so here's a list of games that I like a lot, in no particular order:
- SOMA
- Ocarina of Time
- Saints Row 2-4
- Half-Life franchise + the spin offs
- Grand Theft Auto 5 and San Andreas
- Dark Souls
- Blockland
It's stange how no one has tried to make a "Blockland, but better" so far, and what I mean with better is more tools, more possibilities, higher brick limit, better performance etc.