Every coin in the coinmarketcap or the market is the best coin you can buy because all coins will increase although we don't know how higher the price can go. But it depends on how much money you have and make sure that before you buy any coins, you should analize and decide to buy a cheap coin or expensive coins so you can directly buy the coins. And don't forget to not buy the coin with all in of your money because you need to have free money in your balance to prevent if there are any down for the price so you can buy more the coin.