Is there one that is truly decentralized? On Steemit, minority voices can be effectively muted when more powerful entities start voting down every single thing you published. The company is also US based and the government can hop in and shut down its blockchain if it wants to.
To be truly decentralized one needs to be truly anonymous. Otherwise it is easy for governments to plant a “poison pill” and then use it as an excuse to shut down the entire operation.
I think Nexus is configured so that it is virtually impossible for the government to shut down. But in general, decentralized blockchain is supposed to be invulnerable to the whims of a central player like a government. However, the US government has veto power on most things.
Nobody can shut down a blockchain when setup right; Even the Steem blockchain; Steem has witness nodes running the blockchain and some of them are not in the USA, they are in Europe and Asia, out of control of USA government.
Anonymity drives more illegal actions, and drives the 'hunt of' since the most important element to keep a group of people, a community alive, is taken away: "Social Control".
More importantly, at Steem indeed a few can shut the mouths of almost anybody! Since most of the users are anonymous at Steemit, including those big whales, it is easy to go into war with some others on the platform since nobody is able to find the real person behind an account going to war.