The Datejust.
They are both very attractive watches, and while I prefer the execution of the date window on the DJ, that's obviously subjective.
On the other hand, the bracelet and clasp on the DJ is much better, and the DJ is thinner at just over 11mm vs the ATs 13mm and change.
My Nomos Ludwig 41 has a satisfyingly loud tick, presumably due to case thinness.
I find their iconic stuff too busy, and their newer stuff (like the dive watches with the mallet hands) really ugly.
All entirely subjective, YMMV.
My limit is £7K - £8K, but I really tend to look around the £5K bracket, and I almost always buy used rather than new.
I don't tend to have more than five watches (plus a couple of G-Shocks), so if I buy a new watch it is replacing an existing one.
Seiko understate both the actual accuracy of their watches, and their water resistance.
I get the impression that Seiko would rather underestimate the specifications of their watches, than to be appear to be untruthful. I also think that the Swatch group take the opposite point of view.