Expanding Review Platforms for IT Outsourcing: Expert Recommendations

I may be doing some consulting with a global IT outsourcer. They are working on website and update. In terms of review sites they feature they’re only using Clutch AI and Goodfirm, which are specific to outsourced tech. Should they also add G2, Gartner, PeerSpot and TrustRadius to their efforts? What would you recommend?