My top games from lowest to highest would be...
Suikoden II: Completed five files, played between 20-30 files due to restarts. Estimating over 750 hours.
Final Fantasy X: Currently about to complete my eighth file and have played 15-20 times due to restarts. I have one file where I unlocked everything save stat maxing and monster capturing (did the MC in two separate files.) I estimate over 1,000 hours. (Last year I finished the game three times)
Lunar Silver Star Story Complete: Completed thirteen files and have over 30 files unfinished by now I imagine as much like Suikoden I restarted often. Lunar has reached a strange tradition as I realized it is the only game I own which I have completed at least once every year, thus I continue the tradition now. I estimate over 1,000 hours as Lunar is not a long game.
NHL 07: I spent literally hours with Dynasty mode, wheeling and dealing, numerous restarts though. The gameplay was quite addictive, evermore so as the series progressed. NHL 07 alone I reached over a 1,000 hours however overall between 07, 08 and 09? We're pushing close to 2,000 easily if not longer. NHL 10 looks to rival that time on its own... it looks amazing.
Halo 2: This game is the death of me and as ridiculous as this may sound, I have spend over (well over) 3,000 hours over the three years from its release to the release of Halo 3. It may even be 4,000 actually. I spend a sickening amount of time addicted to online and literally would play every single day for a month until I finally went to other games. I have even played Halo 2 while tipsy (Got 14 kills or so and 4 deaths) and even while asleep - I kid you not, I had stayed up over 48 hours and was nodding off as I played, yet was able to still shake it off enough to play, although it was mostly entirely sleep play. Got 12-14 kills and only died 3 times.
Total estimation for the series would be 4,000-5,000 hours. Ironically since I abandoned Halo 2 around the year before Halo 3. I have never again been as in love with the series as I was. Further irony is despite my almost disgusting amount of time on it. I more than realized Halo is not a groundbreaking game. As always refused to be a fanboy.