it really depends on the manga/anime

The good ones usually end fast, as not to add to the confusion, not continue just because other people want it to, and not add plotholes...

Long. Definitely long, so long as it is action packed, and not TOO many fillers...

The golden mean is golden XDDD

I like them short if it has a good ending, but if it ends on a weird note i'm all O_o wtf just happened. Same goes for long ones, but if they just get too long and the plot just turns weird and ridiculous and I keep finding loopholes, i'm all -_-' okay, this need to end now.

2-4 is probably the ideal. Shorter is okay, but the "moderate" length usually gives the story and characters more room to grow. Series longer than that tend to get stretched out and/or overdone.

I find the same rule works the same with non-animated tv series.

There are always exceptions, of course!

I voted for short, because there was no "non-existant" option

It depends on how attached I get to characters

I don't know x3
When I watch an anime or read a manga, is not because of how long it is, but what it is about xD
But I do understand there are some people who have preferences. My cousin, for example, only likes long animes.

Short, I hate taking forever to finish it unless it's that engrossing. Plus I can make fanart sooner.