I have to go with Ioka on this one. He is the more polished and experienced of the two. Also even though he has had a longer pro career, Ioka has taken less damage in his career.
I favour Ioka as well, but Tanaka is a beast and extremely talented. Lets say an upset for him wouldn't surprise me that much. Size and strength probably the main factor here, and as you said, Tanaka hasn't exactly been hard to find.
Tanaka's other main problem is his samurai mentality. In his fights against Kimura and Cp Freshmart for example would have been much easier if didn't start making it a war. Though Tanaka is my boy and I'm rooting for him.
