Funny everyone says that. You see, I agree Uncharted 2 is the best single player of all time, although... my number one game ever is Goldeneye, but obviously that largely due to the multiplayer.
Now for third place it's a close call between Tomb Raider, Resident Evil & Half-Life. Ultimately though, I think it has to be Half-Life. Half-Life 1 though, imo... I never really played the second one so I'm actually going through it now! Started a few weeks ago, don't really get a lot of time to play it but I'm about a third of the way through I think. I like it, a lot, but for me, it just doesn't touch the first one, just doesn't feel as special. Maybe it's something to do with timing, when the first one came out it just blew the competition away.