Just the way it is some times. This year no headliners on any stage really excited me when they were announced. A few were options but no must sees.
In the end, I saw Idles (really great, glad I made the decision to see them), Coldplay (meh), and Andrew O'Neill's History of Heavy Metal (fabulous).
I don't want to sound patronising but you'll have a great time whoever you end up seeing.
I also got Shed Seven and The Lottery Winners, which has probably swung my decision to go this year as these are two bands who I’d be very happy watching.