The thread-title is really funny to me. motogp (the motorcycle racing league) is in the process of switching the tire supplier from Bridgestone (past 8 years) to Michelin (Starting in march). The tires are pretty different and have different strength and weaknesses, and since we only had a few days of testing in the old year there's lots of speculation on how this is going to effect racing strategies and individual riders. Some say it's going to put everything on it's head, and we're going to see different riders dominating the next season as everybody will be busy to adapt.
So everytime I see Bridgestone vs. Michelin I come in here expecting discussions of this type only to be let down by discussions of economy, longevity and saving cents. ^^
For what it's worth, Bridgestone has been the supplier of many car brands for the past years, among them BMW. And just about everyone there hates them for how loud they are or how bad they drive (traction as well as comfort-wise). And they complain that they last forever and that they'll just swap them out straight away, rather than wait before the tread wears down. So if the goal is to save, I guess Bridgestone will be fine. I am sure a good deal can be made, if you are looking for tire sizes that are common on current BMW models (16-17" and 205/55 to 225/50).