OK.Now i'm fed up with Just Cause 2 ,and i'm looking for a new " sandbox " style game . Which one to choose ?

Here, have a look at this thread:
http://www.gog.com/en/forum/general/best_sandbox_games/page1

Some great recommendations there! Thanks GoG!
From the suggestions, I'm inclined to try Xenus 2 White Gold or whatever it's called.

Warband is a bit repetitive, and has some of the most frustrating online known to man. VERY skill-based online. Problem is, most of the players know of stuff the game never explains.

Pains me, but I'd go Terraria or Minecraft and just buy Warband on sale.

I don't think you'll go wrong with any of them, they're all highly recommended.

I would say Warband.

Minecraft gets quite boring after a while, thought it might be better playing online (I haven't played it online)

Terraria is hard as **** for me, don't really know yet if I like it or not.

But Warband is pure gold. Definately a game to get :)

I'd say Terraria, personally, I quite enjoy it.
My full take on it can be found here: http://zolgar.blogspot.com/2011/07/terraria.html

I have to ask as I always do when people say this, how long has it been since you've tried it? The frequent updates mean that it might be a very different game today from when you last played it. When I first tried it, I also thought it was neat, but quickly boring. Today, I love the game. Also, the next scheduled update will be "The Adventure Update", which will bring a slew of new content to the game.

1.6.3 is the latest version I've played, I think...Can't be sure though...

Do you feel like Legos, or laser tag? I haven't played Terreria, so I don't know where that stands. Between Warband, or Minecraft you should base your decision on weather you want to create and explore (Minecraft) or fight and conquer (Warband). The combat in Minecraft is fun and interesting, but its really only there for flavor and added challenge. It makes the game much more interesting, but its not really a focal point of the game. Or at least it wasn't last time I played it. It will play a much bigger role with all the adventure stuff. Warband on the other hand is built around the combat.

Warband, that game is massive

Terraria is considered a bit tough by some, cause its got no dedicated tutorial. you are just dropped of somewhere and monsters start to thrash the player in no time...
but really, if you learn to play the game and survive its a lot of fun, and multiplayer is awesome

Okay, that's not so long ago then. You might want to give it another try once 1.8 is out, but maybe it's just not your kind of game.

I think I just got an overdose of it :D

Played it like a maniac, and then it got borish :D

Ah, been there, done that. I always return to it though. Right now, I'm trying out the newly released mod The Aether, which adds another dimension apart from The Nether. I haven't actually gotten to The Aether yet though, as you need glowstone to build a portal to there, and I started a new world to test the mod.

Depends on your playing stile. In Warband, you have to grind like crazy, but the rewards are out of this world (assaulting a castle, defending it, fighting for your life on some godforsaken sand dune...). Needles to say, I've sunk countless hours into M&B and Warband. In fact, I've played M&B since 0.401 (yeah, you read that right ;)