Both Lightning network and Raiden are really good but you can also look at MATIC which is currently focusing on side-chain technologies and CELR which are looking to develop into generalized state channel. SKALE is also a good project which is also focusing on the side-chain.
Thanks for the tip. It looks like the aforementioned projects are active in development and innovation. Most of all, they're production-ready, meaning that they can be used on the ETH chain for mainstream transactions just like it's the case with Bitcoin's Lightning Network today. I think both projects have good potential to drive ETH's adoption worldwide to the roof. If ETH 2.0 takes a very long time to become a reality, dApp developers can make use of these "Layer-Two" solutions for scalability.
Speaking of "Layer-Two", there's a innovative project called "zk-sync" which uses the power of ZK-SNARKS for added privacy on instant and near-free transactions on the ETH blockchain. The possibilities with sidechains and second-layer solutions are endless. But their success will ultimately depend on how many people are using it. If there's no demand of "off-chain" scaling, then the aforementioned projects will fail in the long run. Ultimately, ETH would have to scale "on-chain" one way or another in order to reduce transaction bottleneck as much as possible. I hope we get to see the next iteration of Ethereum by this year's end. Just my thoughts
