What spec, tactical, and set bonus should I be aiming for for my Mara?

Is Carnage the way to go? How is Fury?

When it comes to deciding between Mara specs, it usually comes down to, do you want your damage to be burst or DOTs (damage over time)? If it's the former, you want to go Fury, if it's the latter, Anni. Carnage is also a burst spec, and I used to say to stay away if you're a newer player, but at this point, I don't think it's even worth it for seasoned players.

Regardless of the Mara spec, you want to run Descent of the Fearless Set Bonus. Without it, the new ability, Force Clarity/Rabid Furor is mostly useless.

Since Annihilation is a DOT spec, and the most preferred tacticals for DOT specs are the ones where the main cleave ability refreshes after crits, for Anni, that's Spiteful Saber.

Despite Fury being the best PVP spec of the 3, it does have the worst tacticals of the 3. You could maybe go Perservere to boost your burst window, or Cauterized Coronary for even more sustained DPS, Enraged Crush is pretty fun for cleave, but I think for newer Maras, you'd want to rock the universal Mara tactical of Defel Spliced Genes which refreshes the CD of Force Camo after using Predation. Force Camo, and wise use of said ability is the key to survival a lot of the time as a mara.

If I had to choose between Fury and Anni, I'd go with the former because it's burst is more consistent, in order for DOT specs to be very effective, there needs to be cleave and that may not always happen.