2k8 is a good game but it is far from the best game ever.
That would be NBA Live 2005.
Why NBA Live is better than 2k8. First off, the direct pass is much much better. When you direct pass to a player, it doesn't move him off the 3pt line like in 2k8. So when you have that player spotting up for 3, you can direct pass to him and he actually stays at the 3pt line unlike 2k8.
Also the shooting is much better. In 2k8, everyone has different release points which is highly annoying. You have to lab every different release point, and if you have 2 players who look the same, it's tough in the heat of the moment to remember which release point to use. In NBA Live, all release points where the same.
Nba Live was also easier to play defense in. In 2k8 is mad tough to block a dunk, it's almost impossible. Basacally if you get the dunking animation, it's over for the defense. In Nba Live you could actually block someones dunk like they do in the real NBA.
The AI is also pretty dumb in 2k8. In live it was much better.
Now after 2005, NBA live turned to ****. But as is, NBA Live 2005 is still the best NBA game ever by far, no game even comes close imo.