At the moment, it has no competition and I forsee it remaining this way for a long time. Bitcoin is the premier cryptocurrency and the rest look up to it for ideas and improvements hence it will have no competition until a better cryptocurrency arrives and I don't think it's in the near future.
Bitcoin has lots of competitors but glad to say at this point they are far behind. It is really the first mover that made Bitcoin this popular. As the pioneer and first decentralized blockchain, people was amazed and enthusiastically promote Bitcoin. It effect never waned but I'm afraid he scaling issue will be the biggest set back of Bitcoin if not solved.