I wouldn't give any specific currency because that's totally all for you to decide. But I will give some tips as to what to look for.

You need to identify currencies which are undervalued. Meaning, look for currencies that have a relatively low market cap and a low supply. Now this will tell you that these currencies are not at the top 10 list. Now this is more of a long term investment because you would most probably need to hold these currencies until they start gaining significant value.

Another thing you can do is look for currencies that are at an uptrend or in other words, those which are currently being pumped. This is the right time to enter. And then exit immediately when dumping or downtrend starts. This is more of short term.