NEW YORK (Billboard) - We may have love affairs with all kinds of gimmicky divas, but it takes Christina Aguilera to remind us that singing really matters. That's not to say the pop star's latest release, "Bionic," is all about her voice, a muscular acrobat that's become more elegant with age. Combine it with the inventive work of a diverse cast of producers and you've got the best mainstream pop album of the year thus far. Sure, "Bionic" was made for a post-Lady Gaga world, where the comparisons are inevitable and the sales stakes are high. But from the fidgety intro of the dub-tastic opening title track (produced by Santigold collaborators John Hill & Switch) to punk-brat driving song "My Girls" (produced by Le Tigre, with a guest rap from Peaches) to Aguilera's gloriously restrained delivery on "All I Need" (Sia Furler co-produced the vocals), the 18-song set shows an artist confident enough to take direct cues from her tuned-in creative team. Because she's bold enough to do it her way, Aguilera maintains her reign.