Do not invest in one basket because it is very risky. so invest in BNB and ETH so that you can benefit from both, there are many other altcoins that have potential and you also invest in some
Yes, these two currencies must be in the portfolio of the investor in altcoins ...
Investing in one basket is an aggressive way of investing, you'll make more if you are lucky, but with altcoins, I suggest to learn how to diversify as no strong altcoins that would hold its price which bitcoin dump... for now, the safest coin to invest is bitcoin, but it you like a bigger return, that means you have to gamble on a high risk assets in the altcoins market.