Remember layout across launch
Every time I open XD it opens in the same size window not bothering to remember that I last had the program open across two monitors filling the screens top to bottom, with the preview window open and zoomed into a specific artboard. And, XD never opens a document to the last place I edited it. It's always scrunched up small in the center of the screen.
How about remembering the positions and size of the application windows and the locations within each document I was last editing so I don't need to rearrange my workspace and go searching for where I was the last time I opened a document every single time I open XD.