There are many factors that give San Andreas a boost over it's siblings though, many of which are unique to the game. With the immense success of Grand Theft Auto V (and the love that still exists for Vice City and III), that's a big call. Even now San Andreas holds up as a great game, and is arguably still the best game in the series. The game's world is huge, looks great (perhaps not by today's standards but back then, it was a beautiful thing) and is full of stuff to do, including missions, rampages and hidden collectibles.
Loud, vulgar and proud, San Andreas defines everything that is great about Grand Theft Auto. San Andreas was the final Grand Theft Auto released on the PlayStation 2 and now, 10 whole years later, it's still an unbelievably fun thrill ride. Grand Theft Auto III won acclaim simply for completely changing the series (to great effect) and Vice City benefited from an increased focus on story and mayhem.
Since the dawn of GTA's 3D universe, the series has gone from strength to strength with each game offering something new and different. The name Grand Theft Auto has fast become a mark of quality in gaming.