No currency issues to deal with
Several people have given great responses already and I envy your situation because you have 2 great vehicles to choose from. One additional factor you might consider is that the X3 is built in SC, not germany so BMW does not have to deal with the currency differences which probably accounts for some of the pricing difference between the wagon and the X3. BMW's profit margin should be much stronger on the X3. That said you may also be able to work a better deal with your dealer on the X3. We just picked up my wife's new X3 in Spartansburg and planned a short vacation around it. This is the 3rd BMW we have done this with and it's great.