The BNB that you already have is a good coin. So, you can continue to hold that one or if you still want to go for another coin then I will go with the same thing that other people have commented here which is Bitcoin.

Do not stress yourself by looking for any other cryptocurrency. Just go straight and invest in Bitcoin if you think that you should choose another cryptocurrency to invest that money. If not then continue to hold that BNB it is already a good choice. Don't make the mistake of investing your money in the wrong cryptocurrency and ending up losing it.