Pretty detailed analysis.

Options are a personal thing, so you really need to decide what you want yourself.

My only comment would be to your statement that with 20" wheels you would need to buy winter tires at additional cost, while with 19" you wouldn't. Disagree. The vehicle is transformed in winter with appropriate tires. I think you should plan on buying proper winter tires in your location, whatever wheels you drive on the rest of the year.

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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