Whichever one has a nicer label, since there is really nothing to choose between them. What would be worthwhile is a test result or data on any impact on engine life by using one or the other oil. I don't think that either will have an impact on total cost of ownership over an extended period. Really, in the hundreds of thousands of posts here and elsewhere on 'which oil to use' in a BMW, how many times have you seen photos of a torn-down BMW engine that show damage due to lubricant quality? One of the few sets of photos we did get showed the internals of a BMW six cylinder after 100,000 miles using BMW oil, at BMW-recommended change intervals. It looked pretty darn good.

On a slightly different note, as I read on through the Bav Auto promotional flyer, I saw a recommendation to use Kleen Wheels dust shields to reduce brake dust, as Bav Auto doesn't believe they will have any impact on brake cooling. They lost all credibility at that point, and put themselves squarely in the camp of snake oil salesmen.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue