There are lots of altcoins(well, ICOs) Can anyone suggest some altcoins to buy?
I searched some on ICO listing cites, but it seems a lot of them are paid to be rated high. Some coins have only 100+ members on Telegram...

I know that the price will go up and down but how to find some altcoins that is really doing something revolutionary and worth to invest?
I think that's EOS. That really is a great altcoin and they are cherishing a plan to transform the blockchain technology to a new level. that is blockchain generation 3.0. a bold decision and they are still in the process of research. If you are a venture capitalist, invest in it.