It is been almost ten years in existence in the crypto world but the bitcoin is still dominating no matter how many of altcoins will rival the bitcoin's supremacy in the crypto market, as of today there are many altcoins that offer the best feature of what the bitcoin is lacking of but still crypto investors and enthusiast continue to patronize bitcoin. The more altcoins exist the more trading pair opportunity will be for alts-btc coin trading. The more the merrier.
Bitcoin, while it has a lot of close competition from other altcoins is still the leader of the pack. A few altcoins that are popular in the cryptocurrency market are Ether (Ethereum), Litecoin, Dogecoin, Peercoin, Feathercoin, Zetacoin, Novacoin, etc. Ethereum and Litecoin are seen as Bitcoins closest competitors.