National Geographic has a Your Shot section on their website dedicated to photographers where you can set up a profile and submit up to 15 photos a week. They run assignments with various themes and publish stories based on the submissions they receive for said assignments. I've submitted to a few and recently had one selected for the "My Home" story which was published this week.
This assignment had 7380 submissions and they chose 34 images to publish. The editor of the assignment always comments on each chosen photo with the reasons it spoke to them. Here's my image, my caption and the editor's comment it received.
You can see the other images in the assignment here. There is some amazing work featured with a broad range of interpretations of the theme.
In my Your Shot portfolio which I started in February last year I now have 88 photos and 16 editors' favourites, some of which have had editors' notes added too. I've found some beautiful, inspiring work on the site, it's worth a look!