I have no knowledge of the Ateca whatsoever, but the issue is less about range (all LED lights will be very good for that) but functionality. The iQ lights are fully adaptive matrix lights which, via a camera, ‘read’ the traffic ahead of you. You set your headlights to full beam and then when a vehicle approaches you, or you close in on a vehicle ahead of you, they ‘cut out’ that vehicle from the full beam whilst leaving the spread of the full beam range everywhere else. As the oncoming vehicle passes, or you overtake the vehicle you are following (or it turns off) the zone that has been cut out returns to full beam. It’s quite mesmerising and very clever stuff and is a great safety feature. They do quite a few other things as well. There’s a massive difference between ‘standard’ LED headlights and fully adaptive LED headlights. I have no idea whether the Ateca LED’s are fully adaptive or not, but others will be able to confirm.
Surprised that Chris found the Tiguan to be more expensive. I did a quick check of the standard kit of the Tiguan Elegance versus the top spec Ateca a few months ago and with the sole exception of leather (which is a big omission on the Tiguan and a very expensive option with electric seats at £1,500) the Tiguan Elegance had a lot more kit as standard and some of the things that were missing on the Seat weren’t even available as options. Haven’t got the info at hand now, but well worth doing a detailed spec comparison based upon which features matter to you most.