I use several exchanges at once to spread the risk a bit, as I don't like having a lot money on an exchange.

But every exchange has their positieve and negative things.

To turn fiat into crypto I use Kraken, Bitstamp and GDAX. Although Kraken is being a bit rubbish lately.

For (daily) trading I use Bittrex, Binance, EtherDelta (not easy to use for a beginner) and Waves dex.