They're not bad but there are definitely better options such as Binance. Just remember to treat an exchange as a method of exchange rather than a bank and you'll be fine.
Im not sure about that dude consider okex is in the same tier as binance, i would say okex is equal with binance in terms of features, liquidity, and many more. As long as the exchange site is very reputable and there is no need to feel worried about that.
I think the exchange is no different, which distinguishes only the services and features they provide, and both of them also have advantages and disadvantages, but I have not used okex exchange more to binance for transactions and trading.