I generally do number 1 - while having a high score is nice or comparing my score to others seems interesting, being able tangibly -provide- a challenge (or farm cards) to other newbie players seems fun and a nice way of me giving back to the community after I farmed hardcore from others.
Of course, I don't do it all the time, as I realize that not many people (supposedly) encounter my decks anyway, so it's a on/off type of thing.