That's personal taste, but I think the Sport Line gives you the most black/white contrast which looks great, plus you get the nice supportive sport seats. I have the 18 inch wheels. The ride is not harsh- it's firm and solid.
2005 325xiT Jet Black / Beige - current daily driver
2015 328XGT Luxury Line Black Sapphire/Saddle- on order
2010 528xi Sapphire Black/Black/Dark Poplar - retired
2008 528xi Sapphire Black / Oyster/ 6sp manual - retired
2003 330cic Jet Black / Natural Brown - retired
2001 X-5 3.0 Titanium Siver /Black - retired
BMW CCA Member