I haven’t kept up to date on the Dura Ace/XTR differences between the lower groups. In the past the top groups offered less cassette range than the lower groups.
I don’t know if that still holds true, but there was some merit that if you buy the top group your not going to be using it in lower level performance situation.
I assume you are going with Di2. If so, just compare specs and if everything fits what you want, and buy the highest level.
John