I don't think that matters so much, but couldn't hurt to experiment.
I think smoothness is usually tied to encoding. You want your source material to be the highest quality possible, so that when you start compressing the video you get to retain as much info as possible. Also the bitrates that you encode the video in also lead to playback smoothness. Higher bitrates lead to better smoothness, but after a certain point, you plateau out.
I'm really a novice at this stuff, so I don't know the exact numbers of things
I do know that a 720p video is going to be smaller than a 1080p, so if file size is a matter, 720 is better.