Depending on each person's understanding, we will see the potential as well as the risks of coins in this market. Personally, I have always preferred the best altcoin I know, ETH, but in addition to the trends that accompany each bull market, we will also look at a number of criteria, such as the ability of projects, that is, their problem-solving activity in this market, as well as their transparency in the development process.
ethereum is a good altcoins but i don't see them transparent in development, even the rumored eth 2.0 will launch, not even launch as of today. In my opinion, the criteria as a good altcoin are having a large community, high security and adoption. 
Speaking of ETH does not need too much analysis because it is not nearly what we normally judge like other altcoins, I think other than bitcoin in this space, ETH still has a good position determined and is invincible in many ways.