With 0 or +1 ground weapon upgrades sentries do more dps than stalkers; not sure about +2; pretty sure +3 will make them stronger dps as they gain 2 damage per upgrade due to the vs armored bonus. Sentries also have guardian shield, very powerful tool VS carriers I'm not sure if it reduces each hit interceptors fire by 2, or just 2 overall but without upgrades it'll reduce interceptor damage by 40%-80%; if you counter their weapon upgrades with armor upgrades(or shields) you can basically tank through their damage.
Overall a grouping of sentries, stalkers(because sentries alone are gas heavy), and if you want some air then include void rays(be sure they target the carrier not interceptors to build up damage) A big key is to keep a good guardian shield going to protect your units and focus firing, try that out and see how it goes.
Overall a grouping of sentries, stalkers(because sentries alone are gas heavy), and if you want some air then include void rays(be sure they target the carrier not interceptors to build up damage) A big key is to keep a good guardian shield going to protect your units and focus firing, try that out and see how it goes.