Album of the Year is one of the biggest ACM Awards -- and there are some major contenders this year. Some of country's biggest stars, including Jason Aldean and Miranda Lambert, will go head to head for the coveted title.

Aldean's sixth studio album, Old Boots, New Dirt, debuted at No. 1 across all genres when it was released. It includes the No. 1 hit "Burnin' It Down," but the 15-track record is eclectic.

"My hope is that my fans will see that I’m still staying true to my roots while bringing a new edge to the music,” Aldean explains. “That’s why this album title made sense to me — it just really fits where I am right now."

Country group Little Big Town's Pain Killer is among the nominees, and it's the harmony-focused group's sixth studio album together. The 13-track record includes the unbelievably catchy "Day Drinking," which is one of eight tracks that LBT wrote on the disc.

"We knew the record was going to be called Pain Killer way on into the process because we love that song,” Karen Fairchild tells Rolling Stone Country. "That song is really kind of tongue-in-cheek -- 'Be the person that numbs my pain.' We started talking about tying that thread through the whole record, to ease your pain. Don’t we want the whole record to do that for people, anyway?"

Platinum marked Lambert's fifth consecutive No. 1 debut on the Country Albums chart, and it propelled her into history as the first artist to start her career with five chart-topping albums. She co-wrote eight of the record's 16 tracks; among the disc's songs are several exciting collaborations, such as "Somethin' Bad" with Carrie Underwood, "Smokin' and Drinkin'" with LBT and "All That's Left" with the Time Jumpers. Platinum took home the Best Country Album Grammy Award earlier this year.

Riser is Dierks Bentley's eighth studio record and seventh Top 10 album. Hits "Drunk on a Plane," "Bourbon in Kentucky," "Say You Do" and "I Hold On" are among the tracks on Riser, which debuted at No. 1 on the country chart. Bentley deals with a number of big issues during the 12-track record; it's more reflective and emotional than fans have ever seen him.

The Outsiders from Eric Church became the U.S.'s best-selling country album of 2014, with 811,000 copies sold for the year. It's a record that's meant to be played from start to finish.

"Anybody puts it on shuffle, I”ll come kill them myself," the singer says. "You start with "The Outsiders," you end with "The Joint." There’s two songs on the album, "That’s Damn Rock & Roll" and "Talladega." I love ‘em both, but I don’t love ‘em near as much by themselves as I do in the sequence. The space they get from the songs around them and the space they give the songs around them makes me love those songs more. If you take them out, mix them all up -- totally different album, it’s a totally different journey."

Who do you think will go home with Album of the Year at the 2015 ACM Awards? Vote as often as once an hour in the poll below until the end of the day on April 15. We’ll tabulate the results and use them for our 2015 ACM Awards winners predictions the week before the show.

The 2015 ACM Awards will air live from AT&T Stadium in Arlington, Texas, on April 19 at 8PM ET on CBS.