There are only 5 points in dedicated AA talents for Battleships. The 2-point skill is a 10% increase, which is mathematically sound compared to a Cruiser's 4 points for +20%, but can feel like a small improvement.
The 3 point Talent which helps your Priority Sector is a great choice, though.
Also, remember that AA stacks multiplicatively, so each increase also makes the other increases worth more.
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The Secondary/AA Module Health Upgrade in Slot 1 is a great choice for helping your mounts last longer.
The AA Upgrade in Slot 3 is not something used in any builds that I'm aware of.