Isterio said:
Fairy Tail is the Shounen that resembles One Piece the most, but word. The One Piece fanbase is super aggresive towards Fairy Tail for having similarities but never adresses theirs to Dragon Ball. For One Piece it´s inspiration for everything else it´s a ripoff.
I think this mainly comes from the fact that One Piece (and to be fair, Naruto as well) have plenty of themes, concepts, storylines, etc. that Dragon Ball never touched on and it's clear that Oda has come into his own over the years.
Whereas Mashima plays this manga -extremely- safe and even things that could be considered good about Fairy Tail are done much better in series like Nanatsu, Magi, or his previous work Rave Master. The constant comparisons to One Piece probably just come from it being the most popular manga FT has a lot in common with.