I prefer shorter games. Repetitive side quests bore me often, while shorter games give you something new around every corner, and keep it interesting throughout. But even for short games, a game should be atleast 10 hours long for it to be worth $60 for me.

That's part of the reason I love God Of War. It doesn't artificially lengthen the experience for the sake of providing more "hours" of gameplay, but gives you new and exciting adventure around every corner. However, there are exceptions to both, and in some games with side quests, the main campaign is good enough to keep me hooked. Also, not all short games are good either.

There's really no such thing as a filler quests or repetitive quests in games in my opinion. There's a lot of poorly written quests though. 

I played both dead islands btw. Those games central problem wasn't the side quests but rather gameplay and glitchiness. The characters were terrible. It just they were very rough or just plain unfinished games. A better written storyline, characters and sidequests would of made them both much better games.

Now onto the main topic in this thread. 

If I had to choose between games like any elder scrolls that have a ton of things to do and potentially be able to put thousands of hours into it versus playing something like fable. I'm gonna choose the game that's longer and has more replay value.