I tend to fancy the Omega Shield for the Power Conduit Link ability. My ship builds regardless of class are focused on speed and the Tetryon Rider ability comes in handy against any sort of moving target.
I usually play PUGs so any additional shield stripping ability can be a good bonus if the team is remarkably low on DPS or something.
Adding on to previous posts above, the 2 pc Omega and 2 pc Borg are indeed my favourite for both Tetryon Rider and hull regeneration abilities. I always use the Omega engines and shields, with the Borg deflector.
When I was fresh into STFs I favoured MACO more for its resilience but then I realized speed = defence bonus + easier to react to changing tactical conditions.
M.A.C.O Shield has the power conduit feature, Omega shield has energy wake.
M.A.C.O enhances power to all subsystems while taking damage.
Omega Force shield gives a chance of turn and speed boost. <-- However tooltip says 50% chance and I've SEEN it proc once ever.