My first action after getting out of Helgen and warning the Jarl of Whiterun about the dragons was to go and complete the entire Thieves Guild questline as it's probably my favourite one, and I am wondering whether to go back to the save I made just after completing it so i can go straight to the Dark Brotherhood and do their entire questline instead.
I can think of pros and cons, and I was wondering if you guys can help me decide whether to go back or not.
Pros:
I would lose the fine on my record that appeared after a bard I tried to help stood right in front of me while I was attacking the enemy that was killing him.
I would lose the murder on my record that I gained because the same thing happened with an Imperial during the civil war.
I could do the Forsworn Conspiracy questline properly without bugging it by accidentally going into Nepos's house before I was supposed to.
I would get to do the DB questline which i enjoyed as much as the Thieves Guild questline.
Cons:
Every quest in every major city would no longer be completed.
The civil war will no longer be completed.
The main quest will no longer be completed.
I would no longer be more than half way towards getting the Oblivion Walker achievement.

