None of them are ready to use in a serious capacity yet. However, Sia's network has been live for 2 years now, and people are forming smart contracts, getting paid to host data, and backing up real files on the network. The fundamentals are solid -- it's just Bitcoin with one extra transaction type -- but there's a lot of potential left to be explored.

Based on the Filecoin announcement, they are building something very similar to Sia. It appears to depart from traditional Bitcoin proof-of-work consensus though. I'm looking forward to reading their whitepaper.

Disclaimer: I'm one of the co-founders of Sia.

I was under the impression that you can't currently recover your files from a seed on sia. Is that correct?

I was also wondering if siacoin is LN compatible. Can you speak to that? It looks like there is something similar up, but will I be able to pay for storage with any other LN compatible coin?

I'd have loved to see the value of coins like these that are supposed to provide a specific economic utility have their value essentially determined by it. For instance you could simply mint new bitseconds * mining efficiency each time that someone issues a proof of storage over a given time period. This way the value of bitseconds shouldn't never go above the real price for storage over time.

Obviously you'd need to set the mining efficiency below 1 to encourage people to actually store user files, or else it'd always be more profitable to just store for the mining rewards.

Sia to the moon?

Once upon a time I stumbled upon vitalik's post 'Secret Sharing and Erasure Coding: A Guide for the Aspiring Dropbox Decentralizer'[1] and thought it was the coolest thing since sliced bread. I think storj is a working implementation of that (more or less).

[1]https://blog.ethereum.org/2014/08/16/secret-sharing-erasure-...