In my opinion, you can not exactly predict which coin is going to give you the most profit for investing on it. All three coins you mentioned is actually a good coin to invest on. But i would still suggest you to look for more coins which has potential and invest on those coins. This way you reduce the risk of losing a lot.
Yes. We should know the coin that can give us a big profit. Don't focus in this just three coin, yes this is good coin and can give us a profit and if you think that it is enough to hold so you should buy more.
Sometimes the investment can quickly make a profit. You can choose which coins are suitable for investing that are not bound by time and place. Therefore we must be smart to make huge profits through altcoin.