There’s no legal limit on the number of credit cards 1 person can have and there’s no “best” answer either. What’s more important is that you are able to manage all your different credit cards responsibly. Different credit cards have different purposes, so you may find it useful to have more than 1 type in your wallet.
What might impact your chances of getting another credit card is your credit score and income. If you have a poor credit score, a low income and existing debt to pay off, you may find it harder to get accepted for another credit card compared to someone with low levels of debt, a high income and a good credit rating. This is because the lender may be concerned about your affordability levels.