What are some of your favorite story arks in the show?

My three favorites are (from 3 to 1): Infinity Clock, Edolas, and Tower of Heaven.

3 place: Tenrou Island
2 place: Tower of Heaven
1 place: Grand Magic Games

1st: Grand magic games
2nd: Infinity clock
3rd: Tenroujima island

1st = gmg 2nd = tenrou 3rd = edolas

I've noticed that Tenrou and the Grand Magic Games are popular choices. I can see why, and I still like those arks, but my favorites are still the same as the were before.

I liked all the Arcs Except for the Filler Arc, but if i had to chose a #1, it be the Tenroujima Island Arc

Natsu, when you say "Filler Ark," do you mean the Dragonoid Ark between the Nirvana and Edolas Arks?

NO, im talking about the infinity Clock arc, i don't consider the dragonoid episodes to be an arc because they were only 5 or 7 episodes.

I don't really consider the Infinity Clock Ark to be a filler ark because it is one of my personal favorites. While I can see that there is very little connection between the events of that ark with any of the others (except for the Oracion Seis and the Earthland counterparts of most of the main antagonists from the Edolas Ark), I still really liked how it unfolded, even though it was kind of a big middle finger to NaLi fans like myself. Besides, would it REALLY be filler if it has two openings dedicated to it and take place in two seasons?
Personally, I rather liked the filler in Fairy Tail. Most of it is rather enjoyable, especially the Changeling between the Galuna and Phantom Lord Arks, and helps slow things down between story arks, but I absolutely hated the episodes dealing with the Dragonoids. It pushed my tolerance for Fairy Tail filler too damn far.