Logic says it would be RS DD. Because he's the most current version, most experienced.
Armored DD seems like a fine choice, but he wasn't operating at his best during that era, afaik. Suffered another nervous breakdown or something. Bushwacker mentions he's not at his best when he manages to tag him - something that always was nigh-impossible.
So, going with Suit. Re-trained by Stick, has even "watched" his master's master in action (Izo), which most likely was a valuable experience.