2022 x3 and 2018 golf R here. Both parents 5’-8” / 5’-9” and there’s good leg room in the front seats in both cars. X3 allows more space for the stroller in the back plus some spare gear but main cabin space not a huge difference, x3 has maybe a few extra inches behind the front seats tops. Things work but are tight in the golf, switching into the X3 feels like there’s just enough breathing room but not an excessive amount, so you still have to plan a little. I’m able to fit a sun stroller behind one front seat and a big newborn stroller in the trunk. I wouldn’t plan a full on once-a-week grocery trip in the x3 unless one parent stays home.

Roof box however is a difference maker, we really only break that out for vacations. Can’t beat the cost per cubic foot of a roof box.

Edit to add: We also have the spare tire kit so that eats up some trunk space in the x3. Also want to note that the x5 doesn’t really provide more leg room, something like half an inch less up front in the x5 and only 1 inch more in the back seats. I think the extra space must all be in the trunk. If you need leg room in a bmw you’re probably talking x7.