XBL - low MC, low supply, and really good distributed tokens - proof of burn. Easy 10x at current price
PIVX - zerocoin protocol about to release
XBY - posign blockchain consensus which makes it unique - static nodes sign the blocks. Also, this is a modular platform with the future of not depending on a specific programming language
ARK - Crosschain interesting project
PIVX is an altcoin clone from Dash and Zcoin, the zerocoin is protocol of Zcoin, it does not have permission to own this protocol. What do you think an altcoin use function from other altcoins have a good future? For me, I do not think it will be famous

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