DL's base Diamond program in some ways is better than UA's GS program:
125% status bonus vs 100% for UA
Free Skyclub access vs none for UA
Choice Benefits (but UA has usable SWU's, so maybe that doesn't count)
and an airline that's arguably more operationally reliable than UA
I am glad to see Delta offer something like 360 to HVC's, if for no other reason than to address the whining about not getting recognition worthy of their spend.