i'm prefer to invest in ethereum, after in 2017 hit new ATH i don't is imposible Ethereum can hit another new ATH and passed 2017 ATH, this is just my speculation about ethereum price in future
Ill go with you since ETH are more active coin compare to LTC and the blockchain of ETH has a good support in this market. If you have extra money its also ok to own some LTC since its a top coin as well but we cant know if the price will pump, or it will continue to drop because of no development.