In my opinion you can choose a coin that has a high 24-hour volume on an Exchange, my experience is that we can get quick profits by day trading with coins like that. If you trade on Binance then look at the top what coins have high volume, then choose it.
Choosing based on volume is the thing, I guess most traders are following because when a coin is having decent volume then it may not get dumped/pumped suddenly. But, volume along with more number of trades alone will give you exact right coin for day-trading because some devs will manipulate their own coin by showing big volume with the help of shit exchanges. In that case, we can easily figure out them by checking how many trades happened in last 24 hrs.
But, not all the exchanges are showing how many trades happened in last 24 hours. This may be the catch to traders to mislead them toward manipulated coins. It is always better not to go for day trading and even if you go just day-trade bitcoin against fiats as it will always have plenty of volume.