Peercoin, NXT, NEM, Ethereum, and Bitshares are all useless because:
bounded entropy, recursive systems are not decentralized by definition.
They're selling the equivalent of stocks of a centralized company illegally while claiming it's a decentralized currency. They are flat out scams.
Why proof of stake has no value:
Since Satoshi did not solve the Byzantine generals problem, this means confirmations are completely arbitrary. So why are two confirmations more useful in Bitcoin (PoW) than one? Because it's an open entropy system where over a period of time, it's either unlikely or statistically impossible for someone to maintain a monopoly on block validation when there is no upper limit to confirmations.
Recursive systems like proof of stake tend to permanently monopolize block validation by design, with no real fault or state recovery to fix it once it goes off the rails. This makes a proof of stake confirmation essentially worthless due to being a bounded entropy system.
On top of being worthless, proof of stake is also a permissioned ledger since the purpose of mining in Bitcoin is to create a permanent decentralized exchange peg, which thus results in a permissionless system.
This leaves only things like Bitcoin, ring signatures and zk-snarks for anonymity add-ons, things like Lightning Network whitepaper, then there's just a truckload of theoretical changes to Bitcoin that have whitepapers such as weak blocks/Bitcoin NG, etc.
