I would steer clear of HitBTC. All sorts of red flags there. Kucoin on the other hand is solid, no complaints so far.
I'd seen this thread yesterday but was reluctant to be the first one to post in it, since I haven't used HitBTC and thus couldn't compare the two. Interesting to hear that they're insolvent--don't know if that's true or not, but if it is then it's a pretty clear choice.
I do use Kucoin occasionally, and they're a pretty decent exchange. They're almost as good as Binance, which I'd also recommend to anyone who wants to trade altcoins. Kucoin has a
lot of coins listed, and their fees are more than reasonable. I've never had an issue with them that required me contacting their customer service department, and that's a rarity in the world of exchanges.
Hopefully Kucoin remains solvent and intact. You never know if that's going to be true of any exchange, given the history of a lot of them.