Weakest in my own opinion.
If I offended you, apologies, but the bonuses of the armor company along with the Pershing, and the Howitzer and Rangers of the Infantry, I think they beat the Airbourne infantry.
Pumas arn't the problem.
The problem is that Pumas have a +1 VS Airbourne when they are landing. That is when the infantry is helpless because they can't fight back.
By late game, Ostwinds solve that problem, making the infantry MORE risky. Well, while landing anyway.