I would say ETH, it has huge potential growth. The competitors are a long way behind, and whilst they may also be successful, ETH has a big established presence with the EEA.
Of course ETH. The other is nothing as compared to ETH. ETH has a firm status in the market and is popular as well. SO when the future expectations are high, people will go for investment like they are doing now to maximize their future profits. ETH is already demanded by so many people and you will be surprised to see there are as many as 1.3million ETH wallets in the blockchain if you pick the data for 2017.
LTC is nothing compared to ETH? You would have to compare coins in the same class, actually, and this is where the oranges start to look less like apples. I have grown to have some respect for Ethereum over the last months, though not yet converted to their cause, whatever it is. I even bought a little for mid term holding, but ETH's status in the market is derived from all its marketing push and currently game apps. Don't tell me about utility tokens and commercial dapps other than games. Take a look at tx on networks and it all speaks for itself.
LTC is aimin to become a payment class coin but ethereum is a social platform where companies can use it but games can use it also. Remember old days, ethereum blockchain was congested due to a game platform.
I would pick ETH over LTC honestly.