I like a little of both...
You have to consider Open world offers more replayability, bigger levels, usually longer singleplayer campain, uses a lot of the same rooms dungens etc..
Linear games usually have a better story. more detailed cutscenes, usually better graphics, online is usually more polished...
Like I said, I like the ability to acomplish a task, then go into a linear mode where I have to do something, then repeat with innovation...what's your take on this?