Story Arcs

[Nonky]

I don't think I can really answer this; it varies too much from anime to anime.

For example, I really enjoyed the series long story arcs, like in Guilty Crown (despite it's disappointing ending), but on the other hand I find TWGOK's and Amagami SS' multi-episode story arcs interesting at the same time. Single episode story arcs have to be extremely good to pull of because there is limited time to develop a plausible and interesting plot although it works really nicely in comedy anime such as Daily Lives of High School Boys. Also season long story arcs, like in Spice and Wolf, are fine too.

All in all it varies from anime to anime too much for me to say which one is better than the other.

[SnowStorm]

I think it varies depending on the genre of the anime.
But I usually like multi episode arcs. They have a good storyline and aren't as long as season arcs.

I like episode arcs when it's a comedy series like kimi to boku

[KiraTaichou]

Long/Multi Episode Arcs. Short Arcs can be good but I prefer long Arcs because it gives the possibilty to make the story deeper. You can also make more unpredictable plot twists, making the story more interesting. I also just hate the beginning of new Arcs (the Fullbring Arc in Bleach excluded), simply because they have to "rebuild" the whole interest.

[Bato_Kusanagi]

I like the series long arcs more. It makes the series feel like it has a point. Something like Last Exile. But Cowboy Bebop, Planetes and Black Lagoon makes perfect usage of the one episode arc style, so I like that one too.