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?
It's hard to tell whether a coins from ICO is good or not. It's all up to you to understand what the project and the platform is or if it's good to invest or not. Just read the roadmap if you are going to invest in ICO then do some more research about it. Don't just ask for suggestions because sometimes suggested coins would not perform well.