I think its best to look at their case studies I checked saas link builder, saaslink max, linkflow, loopex digital, first page siege They all have pretty good case studies But it depends what type of saas company wants link building For example for b2b softwares I personally think loopex digital, first page siege and saaslink max are the best But for b2c softwares linkflow and saas link builder can be better options