Usually, the profitable coins that are just good for short-term investment nowadays are projects without a strong foundation and mostly carried by the hype which is too risky. If you want sure profit, I suggest that you'll focus on well-established coins. Though it will take time for you to gain your target profit, at least you'll have assurance that you won't put your funds in bubble coins.
The established coins are none other than the top coins like Bitcoin, Ethereum, BNB and there are many more for sure,
at least with those top coins it's unquestionable and much safer too,
other than that for a long term investment it will be profitable regardless of the current down market conditions