"Such A" Or "What A"?

Hi,

I'd like to know if there's any difference in the use of these two expressions,in this context. For example

"Such a great father"

"What a great father"

"Such a wonderful city"

"What a wonderful city"

Both forms have the same general idea. Here are a couple of comments.

I'm answering the question. Did you like New York when you visited it last week?

What a wonderful city. Commonly said.

Such a wonderful city. Said, but in my opinion more often in a slightly longer form,

eg It's such a wonderful city.

Another illustration. On receiving a gift.

What a beautiful scarf.

This is such a beautiful scarf.

Clive