My final analysis:
Both of these teams are aware of each others' abilities. Sasori is extremely familiar with Kankuro and both Akatsuki are somewhat familiar with Gaara since he had to be captured. Gaara and Kankuro are familiar with both Akatsuki at this point due to info. the Leaf provided. This hurts Sasori and Kakuzu more because their powers are most effective as an unkown.
In terms of abilities Team Akatsuki is at a disadvantage due to the terrain. Gaara is one of the few people who could easily handle 100 puppets due to the enormity of his jutsus. His sand sensing also makes it impossible to sneak up on him. Kakuzu's iron skin jutsu will protect him from the sand, but his inability to fly quickly will allow Gaara to sink him in the desert like he did Kimimaro. Sasori can fly fairly quickly, but a puppets weakness is its joints and Gaara could easily exploit that by using his sand to clog them up. I am also not sure Team Akatsuki could make a jutsu strong enough to make it through Gaara's defenses.
If this thread had come out before the current arc, I might have been inclined to go with the Akatsuki. But Gaara has been a monster in the war. He has been involved in the defeat of 3 kage (beating 2 by himself) without taking a break, and is now fighting Madara. The jutsus and stamina he has shown in this arc is absolutely godly.
As far as intelligence and experience goes, this is the only category Sasori and Kakuzu have an edge in. The databook gives both Akatsuki a perfect score (5) in intelligence. Gaara and Kankuro have a 4 and a 3.5 respectively. If the Akatsuki are capable of pulling a win out in this setting, it would be due almost entirely to superior intelligence.
Lastly, let's take a last look at the environment. There couldn't be a better spot for Gaara to fight. He borders on invincible in a desert. To have any hope of beating him in a desert it is almost required to be able to fly otherwise he can just grab you with the sand under your feet. Both Akatsuki can fly to some extent, but Kakuzu is very slow while flying and Sasori probably can't control his puppets while flying. This is the biggest advantage there is.
For my final analysis, I would give a huge edge to Gaara and Kankuro. As I said earlier, the only way I can see Sasori and Kakuzu winning this would be if they outsmart their opponents.