I've already done the test, although it's a small sample.
Context:
https://www.coh2.org/topic/106984/winter-balance-update-sov-feedback/page/49#post_id846108
Considering all variables: PF is the best AT infantry squad.
Rangers are the infantry squad with the HIGHEST AT dmg output. But you are already paying for a more expensive squad AND puting 50% more munition into them. If they invest equally in term of munitions, 2 zooks, it's probable inferior unless hitting low armor targets/rear armor.
Thx for your intense testing. :-)
In the end both squads are really powerful in the AT segment (too powerful if you ask me) ;-)