If you are looking to hold for 6-12 months at least, here are a few that I find undervalued at the moment:

NEO - this is still undervalued and will become China's Ethereum. Dropped abt 20% over the last week over concerns that has been misunderstood by western media. The Chinese don't allow and build their first blockchain just to abandon it.

OMG - this is a nobrainer as the mother company Omise has 50k+ merchants ready to adopt it when they go to their own blockchain in Q1-2018. It will also cater for the 70%+ unbanked people in south east Asia. Still undervalued but rising rapidly and more news to come in Sep.

Lisk - going to rebrand in Sep and has great potential. So far there has been close to zero marketing. Major release in Dec-17 and value should shoot up before end of year.

Golem - you can buy them close to the value on their balance sheet. Provides distributed computing power for CGI - and this is just their first application. Super cheap and has huge potential.