If you can buy and sell token in right time, All coins are profitable. But i would like to suggest you Ethereum, waves and ripple to invest. Moreover, if you want to do short time trading you can use Forkdelta, Idex and Binance as coin Ex-changer.
I agree with you first point that if we buy coins on the right time and sell them on the right time, then all coins could give us profit. But i will prefer Bitcoin than Ethereum. Because bitcoin can suddenly give us profit in a day and i think it will be enough.