if you want to invest for long term, you should invest in ltc,,
this is the silver in cryptocurrency if bitcoin is called the digital gold
I would also vote for litecoin but etc also has its chances. When eth attempts to switch to the proof of stake, people will have to start mining something else. Why not to mine something almost the same? So the price may go up really fast. If eth crashes because of failing the switch, people are also likely to turn to etc, because it was the first version and already crushed before, so that is not likely to happen again. Moreover, as there probably are some real projects that plan to use eth platform, in case of eth failure leaders of those projects will have to react fast and try to save their money. They won't have lots of options, so perhaps they'll turn to etc.