Coilovers. No question.
I was at 70k on my stock XI suspension and I just replaced it last month with coilovers. Best decision I ever made; night and day difference for daily driving.
| E90 335xi 6AT sedan | TiAg | BMS DCI | VRSF Catless DPs | ER Competition FMIC | ER Chargepipe | Tial Q BOV | Cobb Stg2+FMIC LT Agg | KW V1 | Gunmetal VMR V710 | MTEC v4 |