I think ETH is the best. You can see the price from January 2017 till now. The price climbs up. If the price drops , it is just a matter of public acceptance. Now the price is 0.093 above and rises slowly. I predict by july 2017 the price will be above 0.15. If you buy now with your cash 5 k USD you can count the profit of the investment just in a month. Doge? I don't think will have sharp increase so does LTC. Not many progress is done by LTC developers. ETH developer continues to explore application of daaps of smart contract of ETH, That's why the price increase. You'd better register at bittrex.com you can analyze by yourself.