ETH seems the most stable, at least for now thanks to its ERC20. Additionally, consider ICO's. That's what I did - fixed price, nice bonuses, and investments in many projects. Don't forget to read a lot about them, though, as there are many scams. For example, I invested in AgroTechFarm (more info here https://www.coinstaker.com/top-5-icos-that-might-make-you-a-millionaire).
Also, consider Cryptopus - IPFS-based, open-source blockchain tech brokerage marketplace where cryptocurrency investors choose incognito traders based on their result of the job – reputation, history and balance. Trader’s profiles are transparent and their strategies are free-for-all. Very solid team, great project.