Of course, reading whitepaper is one of the important criteria when choosing an ICO. But in my opinion it is better to first study the project team and then do the rest of the analysis of the project.
To me, whitepaper is just basically there to understand more about the project and its business solutions, and trust me, whitepaper can be boring.
Now, considering the fact that whitepapers are easily cloned these days, I really would not want to bother myself too much when it comes to picking the whitepaper first. What is most important is that this project I want to read about, how legitimate is it? This is where the scrutinizing of the team as well as availability of minimum viable product comes in. With these ones, you will know if a project is worth digging in further into or not.