The main animes tend to drag on and on and on.

I have a soft spot in my heart for animes that last between 8-15 episodes. Like Elfen Lied. You're always left wanting more in the end. But that's probably better than overstaying your welcome.

An example of a decently sized/paced anime would be Kenichi the Mightiest Disciple and FMA.

Either way, I haven't watched anime in the last couple of years really. Already have The Walking Dead and Game of Thrones to watch.

Shonen is really easy to turn into a long-runner because the manga gets released every week (if we're talking regular no-slip scheduling here) as opposed to Seinen's once a month. It's a genre specifically catered to young boys to probably sell merchandise and retain their attention.

The last anime I watched was also limited in number: Baccano and Darker Than Black. And those are exquisite. I usually just read manga now because I can't be bothered to keep in touch with time.

I heard that Pokemon Origins episode was very good. I haven't got around to watching it yet.