I would choose Poloniex anytime , Its secure as most of the funds are stored in cold storage , It has the biggest trading volume If we exclude the Chinese exchanges , It's fast , and also have good design and a good support. I don't see a reason why I would choose another platform.
It is secured until it's hacked.What makes you think if they are hacked by the internal team or by random hackers,your money would still be safe ? IMHO,do not trust any trading sites with the money you can't afford to lose.
I think he's saying about only trading. not about storing funds in Poloniex. for the exchange purposes Poloniex is no doubt one of the most trusted platform.. but storing large amount of funds in exchange is not safe.