Of course bitcoin is the best one in terms of trading. Ethereum is a good one because of ICOs. I would propose you to go for ICO's. There are some incredible ICO's which will be the following best altcoins for their stage. Cartaxi is one of them, ARNA was a decent one, at the present time Electroneum is going on effectively. They will be the future in the altcoins and ICO cost will be too low when they succeed.