My daughter and her husband use My Heritage. They subscribe and manage the site, but other family members can access it. I have no idea how it compares with other sites, but I enjoy having it as a record.
I think my daughter put in quite a bit of work checking census records etc and putting the details on the site. Some names are easier than others: looking for a "Clarke" in London or a "Locke" in Scotland wasn't fruitless. When it was all linked up on the site we found tbat some relationships in the last couple of generations were not as we'd been told (birth dates, marriage dates, parentage etc).
My Heritage helps you link up with other family trees which appear to have the same people (place/date of birth, etc); if you want you can check out their trees and "piggyback" on their research, and send personal messages.