As which coin i need to invest in it.
ETH and BNB are altcoins which in my opinion have very good potential lately, especially altcoin BNB really shows a significant increase, many investors are investing BNB and many traders are trading these coins.
That really depends on how long you wish to hold your coins, BNB seems like the best short term option since it has been doing great during the past years, but ethereum is the best coin out of the two and even if it is not going through a good time I really think you can make money with it if you can wait for long enough, so at the end all of this will depend on your goals and your ability as an investor, if I was the one in your shoes out of the two I will select ethereum since I see it as the safer choice.