1. Dragon Age: Origins
2. Final Fantasy XII
3. Mass Effects
4. Dark Souls
5. Oblivion
For me these first 5(ish) are so close that i can't really decide which is best so i just but them down in the order i thought of them.
6. Skyrim
7. Borderlands 2
8. Dark Souls 2
9. Fire Emblem Awakening