While Bitcoin has been the leader of Crypto Currencies since it's inception ... there's recently been some big moves in some other Crypto Currencies lately (when measured on a percentage basis).
Much like how Microsoft was the 800 lb gorilla of the tech world for over a decade, eventually new companies (namely the internet companies) evolved, and from a market cap comparison, are now challenging Microsoft for top spot ... in fact, Google has surpassed Microsoft in market cap value and is now worth $125 Billion more than Microsoft ... and now Amazon and Facebook arent far behind the former 800 lb gorilla ... see market cap comparison below;
Apple = $809 B
https://finance.yahoo.com/quote/AAPL?ltr=1
Google = $658 B
https://finance.yahoo.com/quote/GOOG?ltr=1
Microsoft = $533 B
https://finance.yahoo.com/quote/MSFT?ltr=1
Amazon = $462 B
https://finance.yahoo.com/quote/AMZN?ltr=1
Facebook = $434 B
https://finance.yahoo.com/quote/FB?ltr=1
So while Bitcoin was and still is the 800 lb gorilla of the crypto currency market, valuation metrics appear to show that the competition in crypto currencies is really starting to heat up.
Sources;
For First Time, Bitcoin Accounts for Less Than Half Of Market Cap Of All Cryptocurrencies....
May 16, 2017;
https://www.forbes.com/sites/laurashin/2017/05/16/for-first-time-bitcoin-accounts-for-less-than-half-of-market-cap-of-all-cryptocurrencies/#6fbeb1c66fbe
Bitcoin’s Market Share Falls Below 50%....
May 16, 2017;
https://www.cryptocoinsnews.com/bitcoins-market-share-falls-below-50/