Why I value Domain Authority over Trust Flow

Actually i think most important is you compile all metrics including RD.
You need to see if the rd is 1-10 but tf is 20 then is still a shit.
If rd is 1-10 but DA is 20 is still a shit

Conclusion is all metrics should be decent and similar to each other, then you can call that as a good backlink.

I totally agree with you. The best way is to check manually the RD, anchor text and wayback if you want to build a strong network for yourself. However if you would want to sell links from a network like that I do not think it works.