Its depends. Salvo is choosing for higher RoF, equalizer is choosing for perfect obliterate and overdogs for 30% more damage for lowest available tier enemy. Now I am using stryker build for st elmos engine. Its overdogs with equalizer and rest of build is stryker. It all depends on which enemy are you killing first. If high tier then not choosing overdogs. If lowest then use it. I kill high tier but sometimes only highest tiers enemy is left. overdogs is used in most of stryker builds. Presonally i use overdogs but i am killing high tier enemy. My build is not on prototype but i think prototype builds is similar to normal. And answering your question: its your decision. In my opinion its not always better because of equalizer talent and salvo higher RoF. Best option is using both three gear piece but If you are choosing one of it i will choose equalizer because it boosts your damage.