If you're planning to keep 3 - 7 years,
get one with nav. It'll be very functional.
If you're planning to keep 10+ years,
get one without nav since your nav is gonna be
so outdates/old school look like car phones back in the days.
PAST: 14 F10 M5 | 11 E70 X5M | 08 E90 M3 | 08 E92 335i | 03.5 E46 M3 | 99 E36 M3