My parents choose a RX300 over the X5 for a few reasons:
- Much more comfortable ride vs a X5 with or without a sport package the RX is way smoother.
- Much better bang for the buck, brand new '02 RX300 was a little less than $36,000 out the door with everything cept nav (not many options availbe for the lexus though), compared to deep into the 40s for a similarly loaded X5.
- RX300 has more usable cargo space.
- Better gas milage (although the X5 3.0 gets pretty decent)
- After literally going to the dealer EVERY week with something wrong on our E46 328i my parents were completely fed up with BMW. So far after 22,000 miles the only thing we went back to the dealer for is standard mantience and to have the pin striping re-done where it was peeling off.
Also my parents could care less about the 'performance' of a SUV, they wanted something comfortable, affordable, reliable and fun. If they want a sporty ride they can ride in either my brother's or my M3...
I do think the X5 is styled better, but the RX300 is a better vehicle for what my parents goals are.