The Avengers, definitely. Not only does it look more "superhero" but also is functional as it was made by shield (and Coulson
) Love the sleekness, TFA while good was a bit too armorish and bulky, and the deeper colors on TA suit are much more aesthetic.
And to those who say the TFA suit looks more realistic, I would say that the TA uniform looks like it was actually made by a international intelligence defense entity aka SHIELD. Much more streamlined and uniform-like.