I know Bitcoin is the best, but this case is a little different. I'll try to explain what I mean with a simple example.
If the OP has little money and wants to trade short-term, then altcoins are the best solution for him. Because the capital amount will set the profit amount. If he buys Bitcoin for a few bucks only and the price moves only a little, he will get a small profit.
If you want to look at the best, it's clear that bitcoin is superior to altcoins, since the OP's question concerns "Bitcoins or altcoins". So I try to adapt the narrative to the OP's statement, although there are also those who use altcoins as short-term investments. Bitcoin can also be used like an altcoin buying pattern, by buying gradually according to the ability of the capital you have, even though the profit is smaller and if you use it long term with gradual purchases it will be more profitable for bitcoin.
At least this is what I have been doing for the past year.
But he must remember, not every altcoin can give big profits. Research will be needed.
Research is needed in determining investment in altcoins, especially in choosing fundamental altcoins. However, if a long-term pattern is used, it is also not certain that it can be maximally profitable, altcoins are still quite speculative about their journey, so they require more thorough research before making a decision on the parts in it.