What's your ultimate choice? Or both?

Both are top 2 altcoins in the market, i think you shouldn't hesitate to choose one of the two but should choose both. both have great potential and are worth the long term investment.
You are a newbie and I think you made a wise choice to invest in 2 market-leading projects instead of looking for shitcoins. Invest in ETH and BNB, trust them, they won't let you down.