Looking through a few pages of results for "GuiCreate", neither one seems more commonly used than the other. I'm more inclined to remove AddCtrl, if either.
Code size: According to my measurements (using dumpbin.exe and a script), removing AddCtrl reduces x64 code size by 1120 bytes, while removing Add only gives 264 bytes. The Type property could be removed as well, but saving only another 112 bytes. The difference is probably due to the strings for the method names - Gui.Add, GuiControl.Type and GuiControl.__Class all rely on the same array of strings, so it can't be removed either way. (Side note: GuiControl.Type is redundant; it just removes the "Gui." prefix and gives you the exact string to pass to Gui.Add.)
Future use: Add has more potential for future expansion. For example:
- myGui.Add(Scintilla, ...), where Scintilla is a class derived from GuiControl (or implements the right methods).
- myGui.Add(myChildGui, ...) for better integrating nested GUI windows.
- myGui.Add(hwnd, ...) for windows created by other means, such as CreateWindowEx or an external library.