i think you can get any info about best coins on coinmarketcap, but at this time there are so much coin which price is decreasing, may be the best decision is to buy bitcoin or ethereum for this time
Altcoins are always bound to go down with bitcoin going down, but at the same time, I would not be surprised that at the instance bitcoin picks up, altcoins may actually want to start doing the same. For now, the best coins to buy are the coins with product and not just some empty promises, as this would be the main market that a lot of smart investors will be focused on and even though some shit coins can increase hugely, it is never worth the risk.
Bitcoin and ethereum are very cheap right now. They are the best coins you can buy with this market.
Other than that we also have NEO, a very decent coin. You wont want to miss out a chance to buy more at this price.
Just buy what you know smart people are buying and in that case, you should not be buying empty promises. There are so many fishes in the sea to pick from and you really want to be smart and sure you are not picking the poisonous ones, and in that case, even if you do not want to do proper diligence, it is better to go for the coins that are well known with product and being talked about the most which is bitcoin, Ethereum, neo and the likes. In that way, you will be safer than sorry.