I have completed, or nearly completed, 2, 4, 7, Dirge of Cerberus, 8, 9, 10, 10-2, 12, 13 and 13-2.
I have played some of FFV and VI and Lightning Returns.

Of those games, the only one I'd was total garbage was VIII. But if I were to list the least good games I've played - keeping in mind most of these aren't bad, I just enjoy them the least -

Final Fantasy VIII
Final Fantasy IX
Dirge of Cerberus
Final Fantasy IV
And let's just say FFVIII again.