I'm having a hard time deciding, actually. I'll do a first draft of how I think about this vis a vis the RP restrictions I throw on myself to define my Cmdr's journey through the void!
a) Don't like slave trade, like to disrupt or end slave trade if I do anything related to it!
b) I like me an underdog.
c) For nostalgia's sake from older Elites, I love indeps and Alliance above Feds and Empire.
With that in mind, list:
1. Pranav Antal (I like an indep underdog, and Archon Delaine sells people into slavery while Li-Yong Rui wants to be a corporate NSA/FBI/CIA data collection all-in-one as economic tyrant over Big Galactic Data, so techno-utopian cult it is!)
2. Edmund Mahon (same underdog theory going here, since Feds and Indeps count 2 apiece, Empire counts 4 and there's a pirate king out there but Alliance just gets one, ranking below every Fed and half the Empire to start)
3. Felicia Winters (the Edmund Mahon of the Feds)
4. Aisling Duval (the Felicia Winters of the Empire, and the only one who thinks slavery's a raw deal)
5. Zachary Hudson (if he was ok with slavery he'd be down around Patreus, eff the current Fed administration and eff Hudson personally)
6. Li Yong-Rui (like Hudson he'd be way lower if he allowed trade in slaves, which since he's indep corp idk maybe he does? nothing obvious to show that he does so I imagine he doesn't)
7. Archon Delaine (big-time slaver but not Empire slaver, plus he's a space pirate king so he's got more interests than that and I really like the idea of reaching Rank 5 and having a 100% reduction on penalties for crime)
8. Arissa Lavigny-Duval (barely better than the other Empire slavery-enablers)
9. Denton Patreus (total scum but not as bad as #10)
10. Zemina Torval (literally all about slaves, I kind of want to just pick a Power directly bordering Torval just so I can help grind her into dust)