I would say that the most interesting Altcoins at moment are:
1. Waves
2. SiaCoin
3. Monero
4. Lisk
5. Tronix

Sometimes it's better to look out for coins that are still valued at less than a $1 because that gives them a large room for growth if you get in early enough and do your own due diligence on each coin before investing.
This is just my own two cent