When going to trade, the first thing we pay attention to is the selection of coins that we will use, after that we can choose exchanges for trading.
Because choosing the wrong coins for trading will make us lose, not all coins on popular exchanges are good for trading. So it is very important to
choose the right coins for trading. After finding potential coins, we start choosing a place to trade, Kucoin is a pretty good exchange for trading.
But I recommend using Binance, I see Binance has more choices of coins than Kucoin. After all, there are so many coins listed on Binance that
have the potential for trading, no wonder until now Binance is indeed the best exchange for trading.
He chooses Kucoin instead and probably he feels comfortable using this exchange over Binance. Well, I'd never see any problem with it as it is all just the same strategy to apply. Maybe exchanges will matter as the trading volume will also affect the results of our trade but the most important is we are able to reach our goal and succeed.
In regards to OP asking for the best coin to trade, I suggest choosing coins that seem it look more profitable and long-term. A lot of them, anyway and we need to choose wisely. Seeing a huge trading volume is my preffered.
If he is comfortable using Kucoin, I don't mind it, I understand that everyone has different tastes and criteria in choosing which exchanges to use.
Regarding your advice to choose coins that are profitable for the long term, there are quite a lot of them and usually have a high volume.
Like BTC, ETH, BNB, ADA, SOL, and DOT are potential and safe for long-term trading. From some of the coins I mentioned, now I focus on trading
in BTC, ETH and BNB. Because if I trade too many coins it is difficult to monitor it.