San Andreas was not the best. An unfocused, paper-thin 'take' on GTA, redeemed in some part by the wide suburban landscape, and social backdrop that the game was set in.
Vice City was the one I liked best, even though I greatly enjoyed III, and the two preceding Grand Theft Autos.
SA was an everything and the kitchen sink title, made when people were feeling the interest in a new generation, so they built a game where they stuffed as much as they could, any-which-way into as big of a space as they could. It was playable enough, perhaps, but it was no high watermark for the franchise.