As the question reads. For me:
- The concept/vision - is it innovative? does it solve a real world problem? is the problem it solves something I am interested in?
- The team - Size and experience.
- How the coin relates to the concept. Is the coin a key part of the platform? Are other payment methods available to users, etc.
Three things look for in an ICO, I feel important are;
1. Whitepaper
2. Vision
3. Platform [on what the tokens for the ICO are being build upon]
1. Of course it's obvious they should have a whitepaper
2. Also a commong thing
3. Should
But the bottom line here is, whitepaper , vision and roadmap are easy to create. They can just put good and positive thoughts about the project and that's it. For me the best factor should be "exposure" like devs doing seminars and travels to show what project is or having a regular conference to some crypto related news institution. In that way, we can see that they are serious in the project and all we need to face is the risk of investing to them.