What bike should I buy?

I dont want a Huffey those bikes are gay they used to be good, I have a Mongoose it looks like this: http://www.walmart.com/ip/Mongoose-Deception-29-Men-s-All-Terrain-Bike/14956326 but mine is a hybrid its got a rack on the back of it and I can haul stuff on it and it can go off road its like cross between a mountain bike and a commuter really I bought it from Walmart last year it needs to be able to go fast, be light weight, have a rack on it to carry stuff, but also be able to go off road like on dirt, mud and mountains