Of course the best coins on Coinmarketcap will be the best choice for long term investment. But you should know that how much money you can get almost depend on how long you can hold. Maybe you think 1 or 2 years are really long but sometime it's not enough for a good coin like BTC or ETH to go to the moon, to find out a really good coin for you, at first you should know how long or how many years you're going to hold.