The problem is there are too many main characters: Lucy, Gray and specially Natsu... It makes them slower to power up. In manga like OP, Naruto, Bleach or other big names, the authors show the main chars(and their crew) gets stronger clearly after acts to acts or simply master/control fluently their big power inside so they can battle against stronger enemies. And FT? Almost 300 chapters and Natsu's level basicly still not even get close to the top wizard, he must keep fighting some of the strongest mages in the Fiore and he have never ever beaten them him self.
All the factors that help him get stronger are other people's magic, "will power", they come only when finishing the boss then gone for good? lol, and Natsu back to a normal mage. This scenario happens again again and again. I know that friendship, teamates.. are the important parts for a manga but please? Get Natsu (and may be his teamate lucy gray) some unique training just for him or special power that atleast he can battle himself? S, SS, 10 years, 100 years job and the 400 years(killing Zeref, 100% in the future that Natsu will), so many high lvl events in FT but Natsu still can't overcome even Erza.....
