If you were buying a mountain bike, I'd say thru-axle with no hesitation. The QR is dead in the mountain-bike scene.

You're looking at gravel-grinders. The disadvantage of QR is less there than on a mountain bike. Personally, I would see the thru-axle as a BIG plus. The lack of it wouldn't be a deal breaker, but it would move the needle a long way toward the thru-axle bike. It would take an awful lot to swing that needle back toward a QR bike.

Thru-axles are the future. QR is dead in mountain-bikes, and it'll eventually die in the other disciplines. At least, I hope that it will.