The 2 hour Disable Freighters are some of the best ones as they mostly contribute Contraband and Prisoners. Some other stuff happens as well.
The 8 hour assault ones are good as well, however there is more preference to Prisoners than Contraband.
I'm not really a fan of the 45 minute salvage ones as they tend to return items, data samples, and maybe a random weapon of sorts. I'm more into the Contraband and Prisoners approach as I want to convert as many of them into dilithium. However, the 45 minute salvage mission is also the only mission of this type to be available in Omega Leonis. All others require venturing out into other areas (except Orellius and Gamma Draconis).
2. Execute Mutineers (750), Permit Warrior to Commit HeghBat (626 on crit, white holograms have the crit trait), Execute Changeling (500-2000, +5 contraband on crit)
3. Deport to Imperial Perimeter, Forced Labor Requisition (500 each)
4. Labor Battalion (exploration zones -- 350). This is a good way to get rid of andorian and ferengi prisoners since their negative traits don't hurt the mission the way they hurt the Forced Labor Requisition, Dilithium Mining in Unstable Asteroid Field
5. Labor Battalion (security officer -- 1000). Least efficient prisoner swap, only really good if you don't have the time to get out of Omega Leo, Assist in Demolitions, other generic missions with enhanced dil reward (usually 50 for basic success -- but mind the inputs, some of them aren't worth it)
1. Instigate Defection (blue/purple), ABZ officer exchanges (any color, but green inputs have a strong chance of returning blue or better), Support Expansion*
2. Prisoner Exchange with the Dominion (blue/purple) -- requires dominion fugitives, run Strike Against Fugitive Support Network to acquire.