Bao Dur makes it a lot easier for you to get through the enemy shields on Onderon. That probably gives him the edge over Mandalore IMO, for gameplay reasons.
Also depends what your fighting style is and how you developed these guys. In my game BaoDur was a ranged specialist and Mandalore was a melee specialist. Bao fit my party better. I don't reckon you'll need T3 at all.
I actually sent Mandalore on the mission (which Visas led).
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