Image sequence - if your machine crashes, the power goes out, etc. then the whole animation is lost if rendering to a video format and you have to start rendering at frame 1; if you are rendering to image sequence, you just start from the frame after the last one that was completed.
If you look at the video and find that the codec compression is way too high, render to video format you have to do all the rendering again with new codec settings; image sequence, you just change the codec settings in the video app (Resolve is free) and redo that, no need to re-render.
Those two alone are enough to never, ever render direct to video from your 3D app :)