For each URL on my site, I'm auto-redirecting according to header accept language. The site arch is

English version: http://mydomain.com/page
Spanish version http://es.mydomaina.com/page
etc..

The english version is displayed unless I'm seeing a specific language other than en and that I support in the header, and then a redirect occurs.

Google says this:

For language/country selectors or auto-redirecting homepages, you should add an annotation for the hreflang value "x-default" as well:

My pages aren't language selectors, nor are they the homepage. But I am auto-redirecting.

My question is, should my english version be hreflang="x-default" or/and hrefland="en"?