What is affected by resetting quests?

I just completed the main story line in Diablo 3 and I have option to reset quests. Well, I don't really care if I will have to redo all the game one more time, especially if there is a legendary drop waiting for me at the end - however before I do it I need to know what is reset exactly?

Is it only story line or I will have to upgrade one more time Blacksmith, Jeweler, etc? I suppose that I will lose my companions because they are somehow part of the story.

Solution 1:

The only thing that is reset is your progress, and not even really that, because you can jump around however you wish. All levels, gear, companions and crafting levels carry over. There is even unique dialog when the companions meet themselves in the course of the story.

Most people just play adventure mode as soon as they finish the campaign the first time. It's a much more efficient way of getting gear.

Solution 2:

You get a gold/xp bonus for each quest you complete the first time. Resetting the campaign allows you to gain those bonuses again. Also maybe you need it for completing certain achievements, not sure.

Most people play adventure because the rewards are higher, even with the bonus in mind.