Well your question isn't straight forward but i'd try my best to answer according to the best of my knowledge. Your question seems  two; to trade with either bnb/btc or by investing and waiting for price to increase.

If you are after the trading pair you should go for, i'd say you should choose bitcoin because it has the highest volume and liquidity but if you are looking to invest in them, i'd advice you go for the two because they both have potentials to increase in price over time