First check state laws as some states require no ded glass coverage (i.e. FL). Some insurance companies have glass policies attached to the comp coverage w/ $0 ded. So check your insurance policy. Secondly, the insurance company would like you to go to Safelite (who aren't bad) but you're entitled to go wherever you wish. My advice is to contact your local BMW dealer and or BMW collision shop and ask who does their glass work and then make an appoiment with that person.
Insurance will prob use A/M glass, which I would def inspect first for clarity issues. OEM glass is Pilkington, and even A/M Pilkington is great but won't have the OEM BMW logo on the driver's side. I would stick with Pilkington or PPG (also know as PGW as PPG changed their glass division to Pittsburgh Glass Works). Hope this helps!