Fillers, Non Canon, etc. These things are not related to the plot or manga. Some can be funny to make us like the characters more, while some just make like stupid choices, like in the first anime of FMA, it's filler from the manga a lot, even from the first half it had some noticeable differences and a lot of filler episodes at the beginning(except the light novel episodes). Not to mention the movie, I found it ridiculous. I know that Brotherhood had like a little of filler, but it relates to the manga, like episode 1.
But what do you think of fillers? Do they distract you from the main plot of the manga/anime? Do they entertain or hook you? Do they often annoy you, i.e: Bount Arc in Bleach, OMG, the first filler I've ever seen, and the worst. I wanted to skip it so badly in July, but I just had to finish all 40 episodes of it and I wasted 30% of my summer vacation because of it. And do you get excited when there's like new characters that seem a bit interesting?
At least in FMA they actually worked with the author to make a story
Fillers are generally fine as long as it doesn't interrupt the story and are not too long. Bleach has that issue a lot cuz their story arcs are pretty long and it tends to get interrupted for filler. Naruto had the longevity issue cuz their filler just lasted way too long. If you can provide meaningful filler too, that's a bonus, but I generally don't expect much.
I'm not a massive fan of fillers, especially if they drag on for EVER, but quick one's that don't really effect the main story to much or add new characters that then join in the rest of the show than Im fairly fine with it.
I'm usually not a fan of fillers either, although some are hilarious. I am, however, a fan when it adds something to the story. D.Gray-man, for example had a lot of fillers in the second season, which had little to do with the manga arcs that happened at that time. But, I must add that most of the early filler episodes (for simplicity, those that take place in Western Europe) were for hilarity or expanded on the characters and the background story. Events that only took a few pages in the manga, got a proper episode or two, which made it that more intriguing and exciting to watch. When characters died (like Daisha, who barely got any screentime in the manga and is a loved character thanks tot he anime) I felt more sad for them (not all, of course). But yeah, that really helped to expand the universe of the series a bit. It was also nice that they animated two stories of the first novel.
What I liked about the other fillers, is that the journey from Europe to Asia feels more normal, slower... In the manga they jump continents one page at a time. The fillers didn't feel forced or out of place the first time I watched the series (before reading the manga). Now I want to skip the second season as the third one is my favourite.
I guess what I'm trying to say is that I don't mind fillers as long as they have some purpose (expand on characters or universe mostly), but empty, meaningless episodes can be left out.