Binance has the most volume. you can read more about it on coinmarketcap and go to 'Trade Volume' (top menu)
hmm not really looking for an exchange that the the most volume.
Looking for an exchange that has the largest number of coins.I think in the exchanger that you mention above are very large number of coin so you can check by yourself and find which one you are looking for. But for bittrex i think they dont accept new trader.