BBC News is probably the least-biased, and most competent major news service in the Western world. That's largely because they are more free from corporate pressure and control than just about all the other major sources.
All the corporate media (CNN, Fox, etc) have strong incentives to report only the stories that portray their advertisers and parent corporations in a positive light, in addition to whatever political biases they've adopted for niche-positioning purposes. Even PBS is subject to some corporate pressure, as they are increasingly funded by corporate sponsors. I think this widespread corporate bias is the most dangerous and insidious problem in journalism today, and it's hard to see it getting better anytime soon.