Definitely Stakenet.
XSN was the 3rd project to implement lightning transactions on mainnet, despite helping LTC get up to speed with it. The 2 teams made a collaboration with each other:
https://litecoin-foundation.org/lightning-network-collaboration-with-x-9-developers/Stakenet invented Cold Staking, (Trustless Proof Of Stake)
First POS/MN coin in the world to implement Segwit, Atomic Swaps, And Lightning.
WHY should you pay attention to this? XSN's masternodes will act as the backbone of their entire ecosystem.
They just made their Multi Currency Lightning Wallet available for public beta testing on Linux, and at the end of this week they should be ready with the first test build for android as well.
Even if you DON'T invest, or care about Stakenet, you will still be able to use the wallet to do lightning swaps with the integrated 1-click lightning swaps feature.
As an added bonus there is a TOR-integration as well making all your transactions anonymous.
With all the regulations being forced down on exchanges, this will without a doubt be ground breaking whether you like it or not. USDT will move to lightning soon, this means, you'll be able to tether up anonymously in SECONDS with 100% privacy and without risking your coins on a centralized exchange.
ALL the transaction fees from the wallet is distributed to the masternodes holding the chains (which means you don't need to sync with the wallet at all).
Stakenet Lightning DEXThis one is a real game changer - it's a lightning DEX, which means near INSTANT trades, NO need to sync with the network - masternodes holds the blockchains.
NO KYC
NO RegistrationSince it's running on masternodes, once the DEX is LIVE, the devs WONT be able to take the DEX down, even if they wanted to, THAT'S how decentralized it really is. All trading fees is distributed to masternodes
Decentralized exchanges is the future, it's how Bitcoin was meant to be used in the first place. Peer to Peer!