Although she started out as Lauren Conrad's BFF on Season 1 of The Hills (new season premieres Tuesday, Sept. 29, 10/9c, MTV), Heidi Montag Pratt soon turned into the reality show's resident bad girl. Teaming up with her now-husband Spencer Pratt, Heidi was often at the center of the drama, whether by spreading vicious rumors about LC or catfighting with bartenders who hit on her hubby. This season, former Laguna Beach star Kristin Cavallari returns to reality TV, and judging by the way the devil in a blue dress sashayed into Spencer and Heidi's wedding during last season's finale, Heidi might have some competition. So who do you think will make a better Hills baddie: Heidi or K-Cav? Watch the clip from the new season below.