Modern Final Fantasy (VI+), MMO's excluded (Personal mind you, I know this doesn't reflect popular opinion as VII should be higher)
-FFVI
-FFIX
-FF Tactics
-FFVII
-FFVIII
-FFX
-FFXII
-FFXIII
Didn't play sequels
Mario Kart (console)
-Mario Kart 64
-Super Mario Kart
-Mario Kart U (this would be #1 if not for terrible battle mode)
-Mario Kart Double Dash
-Mario Kart Wii
Super Mario Bros (main console series)... This one is almost impossible actually
1. Super Mario world
2. Super Mario Bros. 3
3. Super Mario 64
4. Super Mario Galaxy
5. Super Mario Bros
6. Super Mario 3d World
7. Super Mario Sunshine
8. Super Mario Bros 2 (NA version I.e. Doki Doki)
9. Super Mario Galaxy 2
Why did I even start this list? For the record Galaxy 2 is excellent and should be higher but, as it was a direct sequel, it didn't have that new feel when I played it. Really, this list is an absolute waste of time as I consider all 9 games listed above masterpieces and, yes, that includes Sunshine. I didn't bother with the new Super Mario Bros sides rollers as I haven't played them yet.
Assassin's Creed Main Installments
1. Assassin's Creed 2
2. Assassin's Creed 4
3. Assassin's Creed 3
4. Assassin's Creed
5. Assassin's Creed Syndicate
6. Assassin's Creed Unity
I haven't played Rogue (heard it was good) or the sequels/handhelds/mobile.