Congrats on the ranking, something I can only dream of.
I'm definitely no expert, but 70/180 owning someone at the top of the rankings suggests they are a better choice than 7/180, as if Mills was a good choice, he would be in more top teams.
Overall, Mills is in 6,782 teams (4%), Haynes 29,241 (17%). Again, that tells me Haynes looks the better option when you compare ratios. A higher percentage of the Haynes selectors are top 180 compared to those with Mills.
One team is playing for finals, the other has checked out. Prefer the GWS player for that reason.
Haynes for me of these two.