Do you believe that Bitcoin, Ethereum, and Litecoin have a good future. Why?
No, i believe only Bitcoin have good future.
Litecoin is just copypaste of bitcoin with minor minor changes (faster blocks, more coins) so it have no future at all or any added value.
Ethereum is just programming challenge for geek's, even author/creator of Ethereum Vitalik don't know what purpose of ethereum is yet. Its just a experiment.