Brutes probably don't need Support most of the time, unless you are playing really high difficulty as a duo or something.
So often something like Kin to take advantage of all the +DMG brutes can leverage.
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But if you do need Survival support then you want complimentary powers rather than stacking I think.
So for a Defense Brute like SR or EA, then Sonic support would really boost their unkillable status.
Or a Resistance Brute like Electric or Rad, then Force Field or Time or Dark.
My thinking is that you will max out the type or survival tools that your Secondary focuses on, thus the support offering additional tools is where it is at.
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The same would go for supporting a scrapper or stalker. Except they need more survival help.
An interesting choice might be to go Blaster instead. Which will easily Out Damage any of those in actual Mission Conditions. In which case a Force Field could actually shine since they would cap defense (for both of the duo eventually) and offer Mez protection to both.