This is a toughie. Who would you pick as the biggest headliner for the 2013 Ultimate PopCrush Music Festival? First Headliners are reserved for veteran pop stars who have embarked on world tours and and know a thing or two about pyrotechnics and engaging thousands at once. We're talking BIG leagues, like Lady Gaga, Beyonce, and Justin Timberlake, who know how to work a stage and entertain for hours.

First on our list is the amazing Queen Bey, who has been touring for decades. Just as she's shown us on her Mrs. Carter World tour, she knows how to turn heads -- be that her glittery (albeit revealing) costumes, legion of backup dancers, or belting vocals. She's a diva (in a perfectionist sort of way), and it shows in her performances. Plus, she's got some moves and a vast discography to chose from, so you never know what hidden gems she'll perform -- helloooo, 'Single Ladies,' please!

Or maybe you would love to see Gaga make her big return on the stage following her hip surgery. Like Bey, she's all about the costumes and imagery. But aside from her entertaining theatrics, we really love seeing her jam out on the piano… and maybe she could perform her upcoming new single everyone's jabbering about.

There's also fit-tastic Pink, who does trapeze-like moves and the Apache Dance during some of her performances (Google her live performances of 'Glitter' and 'Try'). No one else can sing while dangling upside-down. Seriously. Or maybe you're more into just listening to the voices of angels -- in which Adele or Mariah Carey would be a great choice. Although, expect their humor to surface in between songs. Adele's wit (and beauty) has no match.

There's also Adam Levine and Chris Martin, whose respective bands (Maroon 5 and Coldplay) can rock stadiums with their catchy anthems. But don't forget about the neo Rat Pack member, aka tux-lover Justin Timberlake, and R&B crooner Usher, who both deliver dances moves as smooth as their falsettos.

So who will it be? Be sure to vote for the the most important act at the 2013 Ultimate PopCrush Music Festival. Voting will close at 12PM ET on Wednesday, July 31. The final lineup will be announced later that day!