Of course a GM dealer is going to tell you BMWs aren't reliable...
I've had 9 new BMWs since 2001. I had an issue early on with my 2010 X6 50i, and recently had issues with my 2022 X6 M. The others were pretty much trouble free. I can't talk to long term ownership however as I lease them and they go back at about 36K miles.
Good luck.