Artificial Neutral Zig-Zag vs Wye-Delta

I have always wondered about the advantages of a zig-zag grounding transformer versus a wye-delta bank.
The first time that I needed a grounding transformer it was in the third world and I couldn’t find a supplier who even knew what a zig-zag transformer was.
Then and since then I have used a wye-delta connection for an artificial neutral or grounding.
The advantages of the wye-delta solution are:
Usually no lead time.
Easy to find suitable transformers off the shelf.
Suitable replacements may be readily available “off the shelf”.
What are the advantages of a zig-zag transformer, if any?