As pc screen resolution + internet speed has generally evolved, have up'ed the avatar size to (max) 180 x 180.
Due to some constraints in the page layout, 180 width does not display properly in posts, so back to 160 for width, but 180 height is ok. So its 160 x 180 pixels.
For max quality use a .png filetype = larger filesize = better quality.
Anyone wants to update their avatar, just upload a new one in the profile page.
Thanks