Programme: http://roskilde-festival.dk/music/bands/

What are must-hears?

I really like the program and I'm very much interested in hearing recommendations since it's only a few of these bands that I know in terms of live-shows.

Also, there are a few clashes like Savages/Kendrick Lamar; Sigur Ros/Chelsea Light Moving; John Grant/BRMC

What to hear, what to leave and what to choose?