The general consensus is Terra's morph is what gives her the edge though temporary.

My signature has Terra's close max defense. Sabin, without a relic slot, can not use heavy armor from what I can remember. If we remove magic from both of them and the 9999 hp cap, Terra would win.

The exception is they had hp that's very high. Say into the millions and you gave them both a dirk. Sabin's Blitz might beat out the fight command while Terra's morph would end at some point.

I'd say Terra is stronger but Sabin can endure longer. It depends on the situation. But I might as well vote out of bias. I'm also curious what the poll accomplishes besides having fun?