When you say one good altcoins which altcoins are you calling good exactly? They're all the same, neither of the altcoins can be classified as good as no matter how good you think they're and strong community backing, they might have, they can still go in the path of Luna and FTX and crashed but Bitcoin can't. Altcoins are centralized and have a centralized figure that the success of the project is tied to the founders or influencers of the coin. You don't even have to own one Bitcoin, just buy Satoshi and hodl in your wallet.
Bitcoin is superior to all the altcoins in existence so they can never be a better choice above Bitcoin when it comes to investing in cryptocurency. Altcoins lose value over time and even though the coin is trading at a higher price than your buy price, the coin might still be losing when comparing the Bitcoin trading value.