Since you are looking for something passive, then holding is the only passive option in your list; everything else needs your active involvement. On the other hand, the highest rewards you can gain are from ICO investing. However, you need to be extra careful with your pick. Speaking of good projects, I've been eyeing one called MenloOne that's going to launch as a decentralized ICO listing marketplace where its CEO mentioned about having solved the various issues most investors fear in ICOs.  link to their site and Whitepaper: https://www.menlo.one/