Out of all the altcoins OP mentioned I think Ark is the only one I can go with for a long term, there are couple lots of new altcoins now to go with on a long term such as MVL, Binance and Huobi tokens and so many more
in any case, if the project has already released its existing product, then their coins are much more profitable for investments. Moreover, due to the fact that the crypto-currency market is developing very much, it requires a sufficient number of trading platforms to satisfy all the needs of crypto-currency users. Thus coins of trading platforms are also good investments.