Some of the altcoins suitable for diversifying portfolios are those that cost less because you can add many coins to your portfolio with just a small amount of funds.
If you want to diversify your portfolio I don't think it's necessary to buy more coins that don't have strong fundamentals and unclear projects, but you can simply buy fractions of coins that have been proven to give us huge profits like buying 0.1ETH and then holding them for a period of time certain, so as to achieve the profit target that we have set.