antergos-mirrorlist contains mostly mirrors with http protocol, and not the more secure https. Currently there are only two mirrors using https in the Antergos mirror list. That could be easily be changed, since many more of the listed sites already support both https and http for Antergos.
An example: one mirror in the current official antergos-mirrorlist is
Server = http://mirror.de.leaseweb.net/antergos/$repo/$arch
but the site supports also
Server = https://mirror.de.leaseweb.net/antergos/$repo/$arch
This and other similar cases should be added to the official antergos-mirrorlist.