Buying new or used?
If new, X7 is more better, but more money.
X5 is plenty big though.
Don't buy a BMW used....my dad bought a lightly used X5 (off lease but like 20k miles on it)....it was in the shop A LOT, he got fed up and traded it in for Lexus RX and is much happier.
I had a 3 series years ago...engine was fine, but after warranty all doo dads started breaking...including the headliner falling down...loved the car when it was new...nightmare for quality of life after warranty.
Love me some BMW German Engineering, but my BMW purchases will be limited to weekend fun cars if I ever buy one.
I have a Lexus RX for my wife, and it's literally the best car I've ever owned. It checks all the boxes you're looking for. Mine has 93k miles, other than normal wear and tear (tires fluids and brakes), I've only had to replace the battery (once) and the water pump (just done at 92k miles).....it's a tank and super comfy ride. The 3.5L is a rock solid engine and all of the doo dads still work inside. My only gripe is the mpg around town isn't the best (17-18mpg), but on the highway it's surprisingly good (24mpg).
I liked it so much, I got a Lexus when I needed a new car....I'm now a lexus convert.