The Maker token (MKR) is the MakerDAO native token. It acts as a utility token, governance token and a recapitalization tool for the MakerDAO platform, which manages the DAI stablecoin. MKR is used as part of the stabilizing mechanism that is in place to combat the price volatility of the DAI stablecoin.
DAI is pegged to the US dollar and has collateral in place to ensure stability. The MKR token is used is to pay for the "collateralized debt positions" (CDPs) that have been used to generate DAI. After this MKR is used, it is removed from the supply. MKR holders also contribute to the governance of the MakerDAO and vote on crucial issues related to the direction of the DAI stablecoin.

USD Coin is a stablecoin created by Coinbase and Circle. It's backed by USD (1 USDC=$1 USD), and is designed to be a stable digital currency that will fit within the trust and regulatory frameworks of the financial system, while still benefiting from the transparency and advantages of crypto powered networks. USDC is issued using the CENTRE open source framework and membership scheme, and it is available as a framework that multiple companies can leverage. Eventually other financial institutions will be able to become USDC issuers (and issuers of other fiat stablecoins - e.g. EURC, JPYC, GBPC), and customers will be able to tokenize USD and redeem USDC tokens in an open and interoperable ecosystem of financial institutions. A membership governance model for issuers will ensure that they meet technical, operational, regulatory, compliance and audit requirements.

Paxos is a regulated financial company specializing in providing blockchain trust and custodial services for their clients. Paxos' settlement platform (Bankchain) is designed to be integrated with existing systems and to eliminate settlement risk in the exchange of digital assets. The company created a USD backed stablecoin called PAX, that is built on the Ethereum blockchain, and is meant to assist their clients in converting a variety of assets into digital versions, that can be more easily exchanged on a blockchain.