the best web wallet for now only blockchain we can access it from website and mobile app so easy to access and we can set the fees low or high and the security feature is good enough like email and sms verification 
and for friendly reminder that never leave your funds at any exchanges it's not a safe place
CAn you giev the reason why iI shouldnt do this ?,what if i have used my bitcoins to buy alt coins in bittrex let say and wait for some coins to raise in price so that i can further sell them and get more bitcoins ? and for friendly reminder that never leave your funds at any exchanges it's not a safe place