Which cancelled battlecruisers mattered most?

What was the greatest World War I-era capital-ship design lost to treaty cancellation?

The G3 class is the preferred choice, although completed Lexington, Amagi, and Tosa programmes could also have reshaped fleet development.

The British G3 battlecruisers are the preferred choice, although the American Lexingtons and Japanese Amagis and Tosas also have strong claims. Lexington battlecruisers operating with carriers built on the same hull could have formed unusually powerful task groups. Completed G3s would have forced rival navies to reconsider their own programmes. Cancelling these ships changed the competitive development of whole fleets.