I like a mountain bike with hybrid tyres (crossed between mountain bike tyres, and road bike tyres). They are great for basically all terrain, when you have to alternate between bitumen, and dirt tracks. Road bikes are designed for speed, but they aren't built to handle rough terrain. You will bust the thin tyres, and bend the rims, which will soon-after need to be replaced. Obviously, BMX bikes are not fantastic for commuting longer distances. Normal, standard mountain bikes are good also, but opting for the thinner tyres makes it worlds easier to pick up, and maintain, speed.
Definately the best choice for commuting, in my opinion. But if you are ABSOLUTELY CERTAIN that you will be on bitumen 100%, you could choose a road bike. But only if you are 100% certain. Otherwise you will have to keep replacing parts, and it's not worth the hassle. The body-metal is also thinner, whereas mountain bikes were built to be sturdy.