I tend to prefer MP4 over other formats especially for TF clips because I can watch them on Quicktime player. Quicktime player has this special feature that allows me to watch the process in detail, which is being able to have the clip slowly move from one frame to another either backward or forward by pressing side-arrow keys while the clip is paused. AVI and SWF on the other hand, aren't supported by Quicktime player
Anyway, good luck!