I'm sure everyone will suggest investing in ethereum compared to BAT. Ethereum and BAT are both good altcoins, but if you invest, of course I would suggest and choose ethereum. Maybe because ethereum is better and has the potential in the future.
Definitely because ETH is the most popular coin in the altcoins market and currently the top 1.
BAT is also a good token, but in terms of success, it was not as successful as ETH and it was created under ETH platform, so ETH will also be the boss.
During the popular moments of ICO, most projects like ETH tokens raise ETH to finance the project and that's the time where ETH gets more popular.
If one is to hold longer, I suggest to buy both, but for short term, no doubt ETH is the best coin between the two.