There are many aspects to a series that can make or break it such as art style, animation, character design, story, world building, voice acting, music and other misc stuff. I've enjoyed a few series for difference reasons, like A Trail of Blood because the art style adds a whole different feeling to the story, or Dr Stone because I find the concept something different to what you normally have, and the approach to progress is often presented in a fun manner. But what about other people? what do you look for?