Adwords is best in all areas.
In fact, in some countries, the adoption of Bing is much lower to the point that, even if you threw money at it, it'll struggle to spend anything due to the low audience figures. This is from first hand experience.
Have to admit though, Adwords is extremely competitive, especially in areas of hosting. But you have to make sure you're selective over where you compete and that's determined by the flexibility of targeting options and methods you get in Adwords.