So Far, I have been using two exchanges for more than a year, Bittrex and Poloniex and never been encountered or lost coins with them, although admittedly they do have some support problems as sometimes took days and need further follow ups to twitter before doing an action although the problem still solved, what I been always doing is that always enabled 2FA, some sort of added security.
Never encountered any problems? Where were you when there was a DDoS attack at Polo?
I lost my altcoins (not BTC because I didn't have any in my account at that time) and many complained they lost their Bitcoins too, that's a different thing that they managed to get out of the attack without any harm to the capital of their users and credited our accounts back in 48 - 72 hours.
I think that if OP manages to be a bit more careful and feasibly does his transactions to the correct exchange address and uses it, then there shouldn't be a problem of a hack. Use Localbitcoins if you feel so scared about going for online deals because that allows you to go for cash transactions too and you may find people who are already in your trust circle.