Definitely trailer 2 because it was masterfully cut/edited. It was quite possibly the most effective, memorable way they could have chosen to introduce the Winter Soldier. There was this great post
on tumblr I saw that gets at the heart of it, imo (just a warning there's flashing gifs at the link so if those give you a headache or if you're epileptic you might wanna avoid it):
#the way they are framing/introducing him is one of my favourite narrative tropes ever #the way you introduce the mythology; the nightmare footprint someone (or something) has left on the world #on a particular world - that vicious fearsome world of espionage and national security in this case #before the thing itself #and if done right; even the introducing of the thing itself is not a true introduction #it only further confuses and disrupts the already amorphous and vague horror of the myth #it doesn't explain or make nice or humanize #that's why the mask and the silence of the winter soldier - in tandem with his visualized and demonstrated prowess at precisely the thing his myth was built on is so powerful
That said I do think the first teaser trailer was really well done, as well. Basically I think the marketing guys achieved exactly what they were supposed to with both the teaser and the theatrical trailer.