I don't really know too much about WeRelate, but it looks very nice and professional. I could not find any of my ancestors on there, so to use it would be a lot of work. When I joined WikiTree I considered both sites.
I don't think Ancestry or My Heritage are ideal as a repository for your information and photos. My Heritage limits the number of people you can have in your tree to, I think, 250 unless you purchase a subscription. Both of them are best for searching for records and not storing them. I find the process of adding sources to Ancestry fairly laborious.
WikiTree also allows you a lot of freedom as far as presentation. The site uses a simple Wiki markup. There are also numerous tools to aid in your research (I stopped counting at 20). We also have quite a few members who write apps that they let us use for free to help; it is really quite amazing. Although it is a collaborative site, meaning other people can make changes to your ancestor's profiles, there are still safeguards to ensure the changes are improvements. We are also able to make what they call free spaces. These can be used for anything you want, such as posting your photos or other information. Each photo would only be posted once to WikiTree and then it can be linked to multiple profiles. It is really very easy.
If I were you, I would test drive a couple of sites and see what works for you. I pay for Ancestry so that I have access to their records and use My Heritage's free option for the DNA matches. My most complete work is at WikiTree.