Activision killed Guitar Hero with the oversaturation and making a video game on a business standpoint, rather than a video game's standpoint. The fact that they recently closed RedOctane and cut half of Neversoft's staff doesn't really help either.
Besides, Rock Band's tour Mode, daily-updated Battle of the Bands, and the high variety of downloadable content puts Guitar Hero behind it. Besides, as much of an improvement GH5 was over World Tour (which had the worst note chart in any music game), the setlist was Band Hero-esque, and Band Hero was really Band Hero for Girls. Then they tried copying Rock Band with HOPO Chords, and song export, and heck, they can't even get half of World Tour/Smash Hits' songs, and they couldn't get Band Hero's entire setlist on Guitar Hero 5. Where were the good days when The Huangs were running Guitar Hero?