Make 'medium' the default size in internal functions instead of 'thumbnail'?

[joemcgill]

Several of our internal function are using 'thumbnail' as the default size parameter. Since the 'thumbnail' size is usually a hard crop and is less likely to result in a srcset, should we switch that default to use the 'medium' size?

[peterwilsoncc]

• wp_get_attachment_image and wp_get_attachment_image_src default to thumbnail
• wp_get_attachment_link defaults to medium

Core is already inconsistent, medium makes sense to me.

[tevko]

:+1:

[jaspermdegroot]

:+1: