Coinbase offer USD to BTC trading and have publicly stated their plans to add other pairs as and when banking arrangements in other jurisdictions are secured. With the seamless integration of wallet and exchange features coinbase has rapidly increased its trading volume and provides decent liquidity on low spreads. Adding their wallet and suite of apps for most mobile devices Coinbase is rapidly becoming an industry leader. The design and ease of use of their trading interface is top of the range. Coinbase has extremely good security practices coupled with insurance on deposits. Including that they also have raised over 100 million USD in funding providing them with a solid capital foundation. Over 97% of funds are kept offline in cold storage USB's or paper wallets. There is two factor authentication on all accounts aswell as other procedures such as SQL injection filters to halt heartbleed bug attacks - they are on top of their game. Fees for trading were set to zero for a period but now the standard model of paying to take liquidity out of the orderbook is set to 0.25%.
At this very moment, Coinbase supports ETH, LINK, XRP, DAI, DASH, LTC, CELO, OXT, NU, GRT, BAND, UMA, YFI, MKR, FIL, ETC, GRAPH, EOS, ALGO, DNT, NMR, OMG, BCH, REP, ZRX, ZEC, REN, UNI, BTC, XTZ, WBTC, BNT, BAL, BAT, KNC, COMP, LRC, MANA, SNX, GNT, XLM, ATOM, CVC, AAVE, and LOOM tokens.