MaidSafe vs Storj vs Sia
Sia's key distinguishing feature is that it's the only platform today which is fully/properly decentralized. If the MaidSafe devs today disappear, I believe all the servers running MaidSafe go with them. If the Storj team disappears, payments stop entirely and anyone using the Storj bridge (most of their users) will not be able to access files. If the Sia devs disappear, everything will continue to work as it currently does (though, bugfixes and feature adds will stop)
Sia distinguishes in two other major ways as well. First, we Sia is the only platform that allows hosts to put up collateral - if a host loses your data, they don't just lose revenue they also lose collateral money that they put up as a promise to keep the data safe. Second, Sia is the only network that gives you full control over which machines your data ends up on. This is good if you want to run a CDN, need to comply with data laws, or have some other reason for favoring a particular region or set of hosts.