I'll be honest with you, if someone finds a good coin to speculate and mining at the beginning, this person will not share easily
We'll only know about a coin like this when it's late and you'll see in a lot of places, youtube etc
The best thing to do if you want to mine something new with potential is to research for your own, here you can find some announcements:
https://bitcointalk.org/index.php?board=159.0Look in Youtube, reddit, twitter, discord channels etc about new projects, and if you believe, you can mine early
My personal opinion, it's difficult to find a coin like that and it demands a lot of time, knowledge and a bit of lucky
Keep mining ETH, RVN, and solid coins, you can sell and buy good projects or keep ETH for some years