for altcoins: bittrex and poloniex
for btc-usd: bitfinex
but if you have no problem and can do it (because of the language barrier), i would suggest you to use chinese exchanges, they are in the top of the btc volumen at the moment, so is the best place to trade.
Bitfinex or bitstamp for bitcoins and big amounts. and poloniex for small amount. I always use that,,