It is best to diversify, increased your chance of a coin hitting it big and mitigates risk. However, long term safe coin with also with a high upside is NEO. It was is the same as Etherum but faster, free to send, backed heavily by the Chinese government which will be the fist country to full adopt blockchain in many peoples opinion. Both ether and NEO have 100 million coins. Neo is $140 ETH is $1100 USD, since it does what ether does and better its more than plausible that one day it over takes ETH in price and market cap. Some coins that were developing on ETH, switched to NEO. Neo is still in the early stages coins just started being built on its platform. Should have a huge year and very minimal risk.

Also I dont like LTC at all but maybe thats just me. The owner, had a fishy connection with coinbase, he was a top person there, convinced them to list LTC, it climbed in price very high. He then sold all his coins at the top and said it was a conflict of interest for him to have them. The price has never been as high as when he sold them. But it wasn't a conflict of interest for him to work at coinbase convince them to list his coin, and then sell it and an ATH by far? Sketchy insider trading IMO, after the bitconnect fiasco, I cant have any respect for LTC (it is not a scam like bitconnect) but the creator, played everyone.