I personally haven't owned any because I'm too cheap. My Mom and Step-dad however have owned all non M: 3 generations of 3 series, a 5 series, a 6 series an X5 and an X3 now. 0 problems with any of them.
Would have had an M6 in that collection but my stepdad passed away in March of 2014. He had plans that summer to finally get the M6 we got to borrow from the dealership for a day.