Antichamber is easily the best puzzle-game I've played till now. This includes the Portal series and its many mods I already played.
While it lacks a story, which helped making the Portal series so extremely popular, I think that the question which is the better puzzle-game is answered with a simple question:
"Which has the better puzzles?"
In my opinion it is Antichamber, which bends the players mind. It forces you to think in different ways. Ways that would seem "illogical" in other games or even in real life.
Solving a problem that seemed impossible is very gratifying. And when you finished this game, other puzzle-games will seem simple as they restrict themselves to what the ordinary player thinks is possible.

If a videogame story is important to you, this game is a must-play.
Most of the "realistic" war games that are released are about you rescuing the world, being a hero and often glorifying war. This game is the opposite to those masses of, often mindless, shooters.
Unlike those games, your characters in this game develop. Their actions and their environment change them, which is something not many games do. It's not a game about saving the world. It's not a game about being a hero. It's a game about the horrors of war. It's a game that, despite not being great in the gameplay-department, stands head and shoulders above most that was released in the in last years and, probably, will be in the following ones.
It's a game that deserves to be played, if you claim that the story is important to you.

This game offers an endless amount of fun, because (unlike CoD and Battlefield) you have custom maps. This means that you won't have to play the same maps over and over again. Free DLC's, almost perfectly balanced classes and hats! What more could you want?