The choice between choosing fates to level or dungeons rests solely on what class it is you're leveling. If you're a tank or healer, you would be a fool to not just chain dungeons until you hit 50. The gear alone on the way to the top should be an incentive. As a DD though, it would be rough. You could que and kill some fates while you wait, but then you can't be in a fate party. Depends too on the caliber of your parties in DF. In a perfect world, find 3 other dependable players at level 1, then just chain dungeons till you hit 50. Making friends, that's is the hard part though, right?