When the market falls it is best to buy coins that go to the top 100. However, I advise you to analyze each and follow the news, because after the fall, not all coins rise. There is fierce competition in this market.
Tp 100 is still a wide number. there are coins there that were not having any development since the market declines. Just keep in track of the top coins that are still having time to make some plans to develop and increase price even the market keeps declining.