I think bitcoin is first crypto currency and bitcoin's value and the trade volume is high than other coins.also this coin has great potential in trading and investments. So I think bitcoin is king of crypto currencies.
Add your opinion, the reason why bitcoin is the King of crypto currency, because bitcoin is the first Crypto, bitcoin is pioneer. Bitcoin marketcap is the biggest and bitcoin is more popular than other Crypto currency.
Bitcoin is always maintaining as the first place on CMC.
I see there is several potential altcoin, But not so popular as bitcoin.
I also see many countries have accepted bitcoin now. It is good thing .