As a former Beemer 5 series owner, I can tell you that they're two different animals. There are really positive things aout the BMW's. However, the best way to buy them is brand new, or with an extended warranty, the parts are so pricey and you have to stay on top of it. Mine seemed to love the shop, I'm very picky though. still, it's a wonderful handling vehicle.
Now, as a 4 time Lexus owner after the Beemer, currently with a GS300, I find it an absolute charm to drive, very comfortable, I'm 6'5" at 205 lbs and it's got what I want. Very reliable and I support the claims by Toyota that Lexus vehicles are built to perfection. The quality and craftmanship are unbelievable.
I once had a 95 LS400 that I sold when it had 289,000 miles, no oil drips and everything worked, windows, stereo, transmission, suspension, etc. Spent maybe 4,000 bucks for replacements/preventive repairs after warranty had expired (This of course, by doing some of the preventative stuff myself and on big items like timing belts, etc. by using a 3rd party shop, not dealership)
My beemer had 173,000 miles when I sold it, It had gone through 4 water pumps, timing chain broke at 110,000 miles, all new suspension at 130,000 miles and a complete electrical failure at around 150,000 miles. Spend a lot of jack on that car once warranty had expired, maybe around 10,000 bucks total (also at a third party shop).
Good luck!
Tex