BMW TIS is probably the best thing out there. Covers everything. I've never had a problem that I couldn't solve. The only problem is that repairs are based on BMW's modular approach (e.g. replace a windscreen wiper motor, rather than remove it, strip it and replace the brushes)
2nd best is the Chilton (doesn't cover M engines)
3rd best is the US Haynes (doesn't cover M engines)
I have a Bentley that I've never opened in 10 years!!!