Phenomenal output quality
It's easy to find a video editing website that does the job for you, but there are a scarce few video editors that will produce a fine output quality, and output quality shouldn't be compromised. Because ultimately, a video editor's job should be to improve your work, not deteriorate it.
A video editor that allows you to change the video format should also give you a free hand at changing the video resolution, bitrate, and framerate and should support all sorts of audio and video codecs. This is especially important since the video editor should be a single solution for all to save the hassle of switching to another software for trivial tasks.
Compatible with multiple platforms
An AVI to MP4 converter that works exclusively for one operating software is no good because it limits the accessibility and ease of use to selective devices. When video editing software is compatible with all operating software, it becomes convenient to resume your work whenever you like.