I posted on boardgamegeeks.com and got a lot of answers telling me that the game is a incredible at 3 players, and a BLAST with more. Just like poker I think... It's fun with 3 people, it's awesome with 6-10 people.
Also, the seller (gamer) where we bought the game (specialized store) had StarCraft and TI to sell, StarCraft being more expansive. We talked a lot with him and decided to go with TI because that's our game style.
I finished reading the rules yesterday and I CAN'T WAIT to play. With the Option Rules (sabotage, heroes, Age of Empire, distant suns...) it's like having a board game mixing Star Wars Rebellion (PC game) and GalCiv2... oh, those are my 2 favorite PC strategy games!
So we decided to go with TI, and try to get more gamers if possible. With this kind of game, I'm sure it won't be difficult.
Thanks to all for recommandations.