I mainly believe privacy coin, cloakcoin, monero, and the Z series: Zencash, it's one of my favorites because it has much more than a cryptocurrency and the team has realistic ambition
For me, Ethereum is the most popular altcoin that can br trusted of investment. It is the first coin that I knew along crypto that mostly take by everyone aside from bitcoin. There is where I put my investment and I believe that it will give good profit. All altcoin are supported by ethereum where we can earn it without putting any investment with it.