I made a small fortune from KCS, buying in at between 0.50 - 0.80 USD and selling for just below $15. I still hold a little, but nothing like I once did. It grew so fast that it shot up from about 2% of my portfolio to about 40%! It's a great exchange though and still definitely my favourite.
Binance is also really good. I picked up a lot of BNB really early and really cheaply. I made a big mistake selling it off in little chunks to buy other coins. Now I'm fighting to try to build my BNB back up, but I don't even hold a third of what I once did. With the future of Binance looking decentralised, BNB is a fantastic hodl coin.