This Week’s Question: Linear versus Open-Ended?

Which game model do you prefer, linear games(which guide a player through the game), or open games(non-linear games which allow for more creativity and offer more side quests than a core story). An example of a linear game would be Mario where you have to complete each level to find out something new. An example of an open-ended game would be the Elder Scrolls series. Can games be both effectively, or are they exclusive? What are the positives and negatives of each?