gifski converts video frames to GIF animations using pngquant's fancy features for efficient cross-frame palettes and temporal dithering. It produces animated GIFs that use thousands of colors per frame.
ffmpeg by default uses a fixed palette, making GIFs awfully dithered. Other tools aren't much better — they mostly generate a single not-so-great palette for the entire 256-color animation.
gif.ski is different. It uses pngquant to make unique palette for every frame, and combines colors across frames, using thousands of colors in a GIF. The result is so nice you may not believe it's a GIF, but it really is 100% GIF.
Only gotcha: GIF as a video format is incredibly inefficient. Don't be surprised when your video clip's filesize balloons when taken back in time to 1989, but hey, it'll work everywhere.
This GIF converter app has exceeded my expectations. It's fast, reliable, and produces stunning results. Plus, the user interface is clean and intuitive (as Sindre always makes them), which makes it a breeze to use. If you're looking for a top-notch GIF converter, give this app a try – you won't be disappointed.
Sindre Sorhus