Luke by Art Baltazar
Frodo at the Ford by John Howe
Avatar Aang by mbuntag on deviantART
An Awful Lot of Running by Claire Hummel
Harry Potter by Jake Parker
Ender by Sam Weber
My current fangirl obsession is Pendleton Ward. This guy is a story powerhouse. Watch a couple of eps of Adventure Time or Bravest Warriors to get a load of his mad genius.
Now ask yourself why you love these characters? In nearly every case, the reason you love them is because you find their story compelling in some way. And that has to do with writing. Whether or not a writer has stellar craft, whether or not they are rehashing an old formula (The Hero's Journey for instance) or creating something crazy original, whether or not you care more about plot or character, if you love the MC, the writer is doing something right.
Now think about the story you're writing. Are the situations in which your MC finds herself compelling enough? Are you torturing him enough? Are you helping her to become the most interesting version of herself? Do he have enough to do? Is she allowed to make decisions and take action? In all the above examples, the MCs get where they are because they DO things within the construct of the story to get there. There might be great character development, lots of details and compelling motivations, but story is what wedges them deep into our heart and consciousness.
STORY = CONFLICT.