These days eth has performed poorly in the market despite its usages in many ico projects but bitcoin is still doing very well even in this bear market.So buying altcoins with btc will give anyone a lot of coins to take home than using eth. Bitcoin is now the way to go. I will rather use bitcoin to trade these days and not eth.
The best option is still Bitcoin because Bitcoin is the king of this market and can decide for the existence of Cryptocurrency. Personally, I only choose BTC to trade and not use ETH because I believe that ETH is just altcoin and is experiencing a lot of issues in recent trading volume.