Looks like TC has a classic case of "OMG I can't wait for this game" syndrome.
Its a disease dude, and the only cure is to chill the f out. GTA V could also be the worst game ever made. How are we supposed to know the answer to this question? Especially since the term "Best" in this example is not and I repeat NOT measurable. There's no superbowl trophy for the last forty years of video games that we can hand to rockstar once this game is made. So will it be the best ever?
The answer is absolutely not. There isn't any person or group of people anywhere who can be considered qualified to make that call.
GTA 5 is going to be another open world game that gives you the illusion of a lot of things to do, and the illusion a lot of interactivity. In reality it'll just a massive game with little to do.
If you want some real interactivity, go play Final Fantasy XI on-line. Anything can happen in that game. Unexpected things can happen in things that you do over and over again. Gather an alliance of 18 players to defeat a huge dragon, if you have what it takes to do that.