Half-Life 2 is probably my overall highest rated game of all time, that or Betrayal at Krondor, both being revolutions in their respective genres with fantastic tech, music and gameplay. For sheer influence I'd have to go with HL2.
Besides those, Baldur's gate I and II stand out as clear 9+ titles for me, perhaps Deus Ex as well. Ocarina of Time is also up there.
I dunno, maybe I'm just too nitpicky...
Ah yeah, I forgot about Half-Life 2. Might be a ten for me actually.
I think you are being stingy with your tens