Why you are asking about bitcoin is obvious but I could not get why you ask about BNB? Just because that you are trading at binance? Do you notice the volume/total trades in last 24 hrs and all other comparable measurements of BTC and BNB with respect to binance exchange itself? If no, and if you are going to make your decision just because of this community's opinion then you are probably get misguided. Make sure you are going to trade only for profits and when all traders usual motivation is like that then trading the high volume coin is high recommended.

I do go trading some unknown coins for the reason for some races or contests. The exchange I do trade is known for conducting such contests on new coins time to time. Other than those race reasons, I never touch any new coins for my trading. Honestly in the past, I tried trading new coins but always I ended up in losses only. I am not saying BNB is a new nor non-potential coin but it would be much better if you choose high liquidity coins to make sure profits out of your TA.