I greatly prefer short series - but not TOO short, 13 episodes leaves me wanting more and/or the series feeling rushed and too many questions left. 25-60 episodes = JUST RIGHT.
One or Two Seasons = Perfect for me.
I wouldn't say I HATE long anime.... but.... well... there are probably only 3 or 4 Long Anime that I genuinely love: Sailor Moon, Maison Ikkoku -- uhm that's all I can think of off hand.
Where as the anime in the 1-3 season length range that I love, I could name easily over 50 series.
In my opinion, short series are more well written, because the editors and creators have to consider where the story is going and how to get there from the start. They don't have filler. Nearly EVERY episode moves the plot and increases character development and interaction.
Of course, there are exceptions, where a short series falls apart and you can tell that it was either a quick buck for merchandising or had poor planning or a poor budget etc all along. - And there are exceptions where a long series manages to stay on focus without rehashing the same plot devices or using too much filler.
I'm just saying generally, the short ones are a bit better.
I also am a COMPLETE odd-ball in this hobby - I have never ever once felt sadness when a series ends (Unless it ends without being finished such as Skip Beat or Nana or Fruits Basket) But Let's say an ending is conclusive and ties up everything neatly, I never feel sadness for more episodes. I simply move on to watch something else 🙂 So that also I think helps to shape my preference for shorter anime.