Favourite all time anime?

I've watched a good deal of anime that I don't know which one to call my favorite. If I had to pick one, it would be Shingeki no Kyojin or Sword Art Online. Both of these anime look great and the storylines are undeniably interesting. What's funny is that I hated Sword Art Online at first - I just couldn't understand how and why was this anime so popular. But one day I gave it a chance, and I'm so glad I did. Since then, I have been watching SAO episodes on a daily basis, and even have a few light novels of this series.
As for AOT, I'm more drawn to the dark atmosphere of this anime. In addition, many well-written characters add a great deal of depth to the entire series, and each episode you watch gives you a sense of satisfaction.