well it all depends on what kind of driving you're going to do. if you want mroe torque and horsepower and an overall more sporty feel i'd go with the X5.
the lexus feels like your driving on pillows, so if you want a more comfortable ride with more comfortable seats and plus the gas milage go with the hybrid.
also the insurance for the X5 is out the roof but im guessing thats not a problem seeing as how its your dads getting it for you