I guess the OP meant investing as in hodling. "Suggest me some coin for mid-term" says it all. However, the poster didn't tell us how long is "mid-term" for them. Three months could be my mid-term while theirs could be six months. You see it's difficult to put a time range with that. Until something is clearly spelt out, it's often difficult to pin it down to something.

Taking the liberty of the fact that they meant investment, I'm suggesting to them to look out for tokens with low cap but which have utility. These tokens will keep rising even if it's at a snail speed.
Dego, Citizens Finance, Cartesi, Curio, Poocoin just to mention but five. Those tokens are great.