Now, I love One Piece. It's a good manga, and I love the characters. I also like Fairy Tail, and lo and behold, I do not start mysteriously burning into ashes -.-. Honestly, if a manga is interesting, then it's interesting. People read what they like so personally, I can only say it's unfair to the creators to compare their works from the beginning. It is inevitable to compare most shounen manga since they do follow certain guidelines - a special hero, his friends who work with him, bad guys to destroy, etc etc, but still. Let's try to view them objectively for the sake of reviewing.
And to all the people who say that Fairy Tail is never defeated, have you read the latest arc? adsfjkl;asdfj;kladfkjl;adfl;jkadf;klj When I read this week's chapter I was waiting for each page to tell me more information. Really well done, Mashima Hiro-sensei. Personally, what I like best about Fairy Tail is the world setting. I also like the characters but in the fact you get to know a little about all the guild members... We don't focus too much on one character for too long, and you get more attached to the guild as a whole, not just our main character, who admittedly, is an idiot. Then again, he realizes he's an idiot? Hmm >.>
The art is similar to Oda-sensei, but then again both he and Mashima Hiro draw inspiration from Akira Toriyama so it's not very surprising that their art styles make come off as similar, especially when comparing artwork from beginning volumes. However, they definitely have their own distinctive styles for certain things if you bother to stare at panels too long. I wouldn't bother so much about similarities in artwork; if you like it, you like it. If you don't, whatever.
tl;dr - this is a good shounen manga. I cried a few times at certain scenes, just like I did with One Piece. These are the only 2 series that have gotten teary-eyed for. And why are you reading this anyway? You should read it for yourself and find out :3