Guided Goals or Achievements?

Most idle/incremental games have either guided goals or achievements, sometimes both. Was wondering what people's impressions were of these

Guided goals are nice in the sense that they guide the player without a real tutorial. Egg Inc. is an example, it will give you a goal/quest to accomplish something, but it's specifically set up to be an action you should be taking soon in the game. The problem with these is that you can work on other parts of the game, then beat the challenge way late, then the next 4 challenges could already be done

Achievements are the alternative, which kind of gives you more freedom to tackle the game as you see fit, but you lose the benefit of the game holding your hand a bit and guiding you

Thoughts?