I'd advice you to do your own personal research. Make out the time; pick randomly on altcoins within the first 50 and analyse their performance and the tendency for them to do better. I have shared some of my research parameters and am not bulging just yet. Inbox me if you don't trust your own analytical method.

After the research, you'll be amazed at what you'll discover.

Going back to your question; i'd suggest;
etherium
eos
Seele