depending on why you want to invest here are 2 options:
1) i would invest in super low priced altcoins. EG grump coin which is at like 2 satoshi's.
yep 0.00000002
if you think about it, there is only 1 chance for the coin to drop. but millions of chances for it to go up.
most of these secret coins are on small exchanges such as
www.cryptorush.in.
2)if your not into coins for a good pump and dump/fast but mayb risky profit, but more for a long term investment. then look for coins that have actual use and functionality.
EG
bitcoin - atleast 30k merchants
litecoins - many merchants
feather coin - a few merchants.
because if no one is 'using' it then long term the price wont hold, as people usually move onto more exciting coins after a few months