The original poster mentioned the inclusion of "great quality."
The first example that you've shown at most has ~10 FPS and 360p resolution, which is of poor quality when compared to other video hosting websites.
The second example does not apply to what I said above because Images-to-GIF is an entirely different bag. Images-to-GIF does not have length limitations, nor does it have an explicit framerate drop. But it does start to lag when too many frames are present due to server limitations, so the framerate is dropped to avoid the aforementioned lag.
Here's an example of a 20 FPS animation that is 1:30 long:
imgflip.com/gif/7lqrvo
It was made with 1000-2000 frames if I recall correctly.