I'm tied. they are both great games, though i like that you have more machine guns and more modern weapons (although they are not modern) than just bolt action rifles. But I really can't decide. Both really awesome games.
They are both very good...honestly, it's difficult to choose a better of the two. 1917 was fun in a more simple yet amazing way, while 1944 brought more strategy and depth to the game. To be completely honest they're both equal to me. But since this whole post is about choosing one...I'd have to go with 1944. That's just me, though.