Well, surely the most influential. All the WWI tropes are here, but still fresh, never seen before. And there are things that have never been bettered- the battle scenes for example. They really are quite extraordinary. The sequence that intercuts a close up of a machine gunner with his view of the men he's killing, panning along the advancing line as they fall, is as powerful a vision of mechanised warfare as exists in any medium.
A myth about the early sound era is that they had to put the cameras in soundproofed cases- which took the movies back twenty years or more and- after the wonderful fluidity of the later silent fims- everything became stagy and static and studio-bound. But none of this applies to All Quiet. The camera pans, dollies, does everything but fly- and maybe it even does that in some of the panoramic shots of the battlefield. There are breathtaking trick shots- like the one right at the beginning where we back out of the street, where the troops are marching, and seamlessly, without a cut, into the classroom where the professor is holding forth.
The script is a little literary and some of the acting (but not that of the two older leads, Louis Wolheim and Slim Summerville) has the over-emphasis and over-statement associated with the silent era. So what? Screen acting was still a work in progress. You could call the movie primitive and it is- in the sense in which Duccio is primitive compared to Michelangelo- but primitive doesn't mean worse.