The cryptocurrency marketplace is starting to get crowded, as more companies launch their initial coin offerings and more emerging branches compete for top places. It is fair to say that all cryptocurrencies at the moment are in direct competition with Bitcoin, the market leader. Though still the largest cryptocurrency by far in terms of reach, market cap, coin value and most other metrics, Bitcoin has lost its market monopoly of 85-90%. It now takes between 4% and 50% of the available crypto trade. However, aside from the competition with the top crypto, there are also emerging rivalries between the other cryptocurrencies on offer. Rival pairs include Bitcoin and Ethereum, Litecoin and Bitcoin Cash, and Ripple and Stellar. While all are battling it out for supremacy in that crypto marketplace, these pairings create some interesting battles - and could even spark price wars which could push the currency values up or down in the future.These are the big two players in the crypto space right now, with Ethereum looking like the only coin capable of challenging Bitcoin's crown. There have even been occasions where the Ethereum market cap has pushed past the value of Bitcoin's, though this never lasts long. Ethereum has the advantage of being seen as 'more legitimate' by investors, with a level of transparency not usually attributed to Bitcoin.Bitcoin Cash is the hard fork of Bitcoin, forged when disagreements over crypto rules forced a breaking away fo the main currency. When this happened, supporters of Bitcoin Cash predicted it would overtake the original Bitcoin in value, and become the market leader. However, its close rival Litecoin looks set to squash those hopes. Litecoin is predicted to rise significantly in 2018, due in part to its inclusion on the Gemini platform and its launch of Litepal.Though neither Ripple nor Stellar has gained the traction of their bigger rivals, both could shine in 2018. Ripple is pushing to form partnerships, both with small startups and with major financial institutions, to create real world use cases for its digital currency. However, hot on its heels is Stellar, which threatens to do all that Ripple promises - but in a far faster and more open manner. Stellar has so far struggled to gain traction against larger rivals, but 2018 could well be the year its star rises.