I have both xenons and halogen lights before, and at one time, I had two type of lights on two different cars. And IMO, xenons look nicer, but it is not necessary.
Also my last bimmer E90, had HK, and I wasn't impressed, and my Merc C class, at the same time as well, so I could do A-B test, had a better sound system in her.
So for my latest X1, I did not order either of them. IMO, both options have zero resale value.