In conditions of constant volatility of the cryptocurrency market, I will choose old coins.
They have proven their viability and growth opportunities upwards.
I also do so, in any case, until the market shows a steady growth, only then you can safely buy new coins and not be afraid that they will not make a profit
If a that new coins will not make profit don't expect to gain fast profit, because it needs longer time to take in order to develop more demands for its crypto community. When you're able to grow your asset you will find good returns once market started to increase at better pumping period, so you might grab more opportunities to sell at profitable price. You won't regret those times you've been patiently waiting and after the struggles rewards always come unexpected.