That is quite a hard question @OP. No one is sure what the price of a certain altcoin is in the next 5 years but if you are so eager to invest, I can say try to look for an altcoin that has a low price, solid foundation, good community, and had been running for some time and yet been pumped hard. You can try to look for a good altcoin that is less than $5 in price because the lower the price of an altcoin is the easier for its price to go up and the profit multiplier to ramp up.
.
Myself too had the same thought. Invest on a low priced altcoin that have got good volume and a team that is committed in development as per the growth happening with cryptomarket. When investing in such coins try to hold a good volume and see if it is in good rank. Though ranking isn't a big thing it also play role while getting added to Exchanges. Invest on coins that are listed on tier 2 exchanges. When this gets listed on tier 1 exchanges, surely we can experience a big price jump. So, plan wise and act accordingly. If luck is on your side you'll be a millionaire after or within the next five years.