1. Kurama: Strong chakra due to Uzumaki Clan bloodline. Skilled in sealing jutsu, particularly Adamantine Sealing Chains which can subdue tailed beasts. Kurama sealed Nine-Tails during the Konoha attack. His inclusion in Akatsuki would greatly help in the Tailed Beast collection.
2. Fugaku: Unmeasurable strength. Activated rare Mangekyo Sharingan willingly during the Third Great Ninja War. Itachi believed Fugaku's power surpassed his. If part of Akatsuki, gathering tailed beasts would be easy.
3. Third Raikage: Considered perfect Raikage. Sacrificed himself to fight thousands of enemies and protect his teammates. Rest would have altered the outcome. Having him in Akatsuki would make collecting-tailed beasts easier.
4. Hōichi the Sage: Wields a biwa. Helped separate tailed beast Matatabi from Jinchuriki. Fought two-tailed beasts alone during Chunin Exams. With him in Akatsuki, collecting tailed beasts would have been quicker. His unique ability, Sealing and Absorption, would aid Akatsuki.