Everyone, what most people don't think about is that Shukakku was trolled REDICULOUSLY because of the method by which he made his one and only apperance in part 1. He was essentially beaten with plot no jutsu as naruto forced Gaara out of his feined sleep technique.
If Gaara had been capable of a legit full Bijuu form like Bee or the other hosts, Naruto, along with Sasuke, Temari, Shikamaru, Shino, Kankuro and anyone else in the Konoha forest would have been destroyed.
It was said that the power of the tailed beasts is NOT ranked by their number of tails, which would make sense because Shukakku was just as feared in Suna as Kurama was in Konoha.
Sandaime did go toe-to-toe with the Hatchibi back in the day, but he ended up spearing himself mortally and nearly died in the process. If he fought a tailed beast with an elemental affinity that counters his own?
I give it to Shukakku. He also has a regenerating sand body