0x project has been one of the most watched out projects and going by their github repo it has a healthy development on their base protocol code and also on supported tools. The 0x protocol allows to trade any Ethereum-based assets that comply with the ERC20 token standard but have plans to support ERC223 tokens in future. As of July 26, 2017, a total of 4269 ERC20 token contracts are registered 0x standard will be preferred by those who want to tokenize traditional securities, currencies and digital goods.
Their competitors can be DEX like OpenLedger, EtherDelta, OmisGo (When their DEX is ready) and also Khyber.network. But by going as a building block approach they have developed a much better strategy where they can improve their technology based on DEX using their platform. And their core team can focus on developing the core Decentralized Exchange protocol and platform rather than managing the risks of running a Decentralized exchange.