GTA is not perfect, and I don't know why they're the most popular games on the market, sure, they're fun, but I find they get boring sooner than later. If it had to be a next gen title it would be MGS3, but of all time, the only perfect game in my eyes is Chrono Trigger. I have played through this game so many times, and it never bores me, its friggin amazing. The Total Gaming package...
And on the second point, to make a game perfect it needs 3 main things, a great story/characters, it has to have fun and in-depth gameplay(see CTs double techs), and a certain replayability. I feel that graphics are the last thing anyone should worry about, unless they make your eyes bleed. Sports games get a pass on the story, but I don't think they'll ever be passed as "Perfect"