We have so many options for investment, and we can choose any coins we want. But for trading, we need to search one by one, so we can find the right coins for trading because, in every day, the altcoin position will always change, so that will make us find the right coins to trade. Once we can find one or more coins, we need to analyze what price we should enter the trade, and we need to find a low price to buy.
It is not only trading that requires you carefully choosing the right coin to invest in, it is very necessary also that you are picky about coins before you invest in them because not all the coins that you see in the market has plan for future, some of them are just here for the temporary, and if you make the mistake of investing in them for a long term, you may end up losing such investment for now.
So, for both Investment and trading, we need to do a very vigorous research and ensure that such project has a product that is really working and will be used by people. Any project without a real case will never increase in value and there will not be much volatility that will make it perfect for trading, and I think the best coins to trade right now lies within the top 20 coins.