Lately I've been hooked on Soul Eater and Fairy Tail as my source of entertainment. Though there's certain things that do bug me, such as obvious plot twists, dry jokes and over-exaggerated characters, there are still things that I thoroughly appreciate - which may be why I have watched nothing but children anime for the past 6 months.
Imperfect but Young Characters
Rather than making perfect characters, the series creator make sure that each character has a flaw that they have to overcome - which we assume they overcome as they grow with age. This makes it really easy for us to side with the character and cheer them on as they overcome their imperfections.
Full of Spirit
Black Star from Soul Eater
Another thing about the protagonists is that they aren't hit with the cautious and hesitant nature of adults. They follow their hearts and go at things full throttle.
Challenge our Assumptions
What I've noticed is that they establish certain roles and relationships that we the audience take as absolute. Examples of these are: Gray and Natsu fight but will always be best friends, Erza is dependable and will always be in the eright, Professor Stein is Shibusen's greatest asset. After making these clear, the series challenge these notions through different events and plot twists. This is a really good way of keeping the viewer engaged.
Igneel from Fairy Tail
The last thing I am going to talk about is that each of these series have a end=point which will signify the end of the narration. For Fairy Tail, it is when Natsu finds Igneel. For Soul Eater, it is when the witches, kishin, and Shinigami end their war. This doesn't necessarily mean that this is how the story will be resolved - it could end with no resolution (i.e.:Natsu accepts that he will not find Igneel) or minor resolution (i.e.: Shibusen beats Arachne but the war can start again in years time). But the magic with this is that there is an end point - we are assured of avoiding a never-ending anime loop that only makes episodes to generate gross income. This is really important for me personally. I appreciate series that focus more on the storyline than stretching episodes or creating a season hit.
Now if you excuse me, I need to watch this week's Fairy Tail =P