Root domain vs. subdomain vs. url

When checking TF and CF in MajesticSEO there is sometimes a big difference between the root domain, subdomain, and url. Should I just go with the highest number or is the root domain the most important?

What are you trying to achieve?

MajesticSEO is one of the tools I use to evaluate expired domains. I thought the metrics for the root domain include those of both the url and subdomain but sometimes I find domains where the url or subdomain has higher TF and CF than the root domain.