The Length
They were all rather short, the College of Winterhold being the shortest and the Dark Brotherhood being the longest. The Dark Brotherhood was only the longest because it required you to do extra side quests, whilst the other ones didn't have such a requirement. Some may argue that the Thieves Guild and even the Companions have required side quests in order to progress, but not nearly to the extent of the Dark Brotherhood. The College of Winterhold was over within three to four hours, especially if you're playing on a lower difficulty and are fast traveling! The Companions can be completed in anywhere between 4 and 5 hours. The Thieves Guild Main Questline can be completed in about 4 or 5 hours, however, restoring the Thieves Guild can take a good chunk of time, like an extra hour or two. The Dark Brotherhood took around pretty much 7 or 8 hours because of the huge amount of side quests! For the Dark Brotherhood, it's Main Quest > Several Contracts > Main Quest > Several Contracts, etc. Which is what makes it so much longer than the rest. All in all, in comparison to Oblivion, they're each shorter, which disappoints me greatly.
The College of Winterhold
When we're not discussing the length of The College of Winterhold and we're just discussing the gameplay, environment, rewards, etc. it truly is somewhere on top. The rewards are definitely worth while if you're playing a mage archetype. The Arch Mage's Robes are truly the best robes I've seen so far, and I've seen a lot of robes on my journeys. Many vendors and trainers are available, which helps out big time. The companions are rather lacking, however. There are a select few radiant quests given that offer over 1,000 gold each, which is an incredibly generous amount compared to all of the other radiant quests I've completed. Now I know what you're thinking, "Sterlin is a hypocrite! He was just bagging on this guild earlier and now he's praising it!" Well if it weren't for the incredibly short questline, I might actually say that this was the best Quest Line to complete in all of Skyrim! Too bad this isn't so. Also, another issue is that even though you're acknowledged as the Arch-Mage ( aka. Guild Master, which is definitely more than I can say about some of the other guilds ), it doesn't compare to the feeling given from the Mages Guild in Oblivion, where there were tons of apprentices that pretty much worshiped you and even made references amongst other guild members about you.
The Companions
The only good thing I can say about this is that the Companions are actually pretty good, not to mention the leveling exploit. Anyways, upon the completion, when you're the guild master, you're again, not left with the same feeling that you may have had in some of the previous Elder Scrolls games when given such a prestigious title. The Radiant Quests give very very small amounts of gold, at least the ones I've completed so far, in fact, the whole questline gives petty rewards. I think I was given only 150 gold for each quest I did, where as in all of the other guilds, I earned at least double that. I felt that some of the quests were rather pointless, and unneeded.
The Thieves Guild
The main gripe about this one is that, upon completion, you have absolutely no feeling of being the Guild Master. People still talk down to you in the guild and they even call you a new-guy. I have yet to restore the Thieves Guild's wealth, but from what I understand, you're still left with the same empty feeling of not aspiring to what you should. The guild's full of side quests to do, but it feels like the rewards aren't worth it at all. For example, I remember I did a quest where I had to steal 500 coins worth of goods in a certain town, I completed this and they took the items I earned and gave me a mere 250 gold, huge rip off. The Lock Picking training is a joke, there's only 5 chests to open and once they've been opened, that's it. The rewards from all but the Master Chest stink. If it wasn't for being a Nightingale I'd say this is my least favorite Guild to complete thus far!
The Dark Brotherhood
There were too many side quests that had to be completed in order to progress in The Dark Brotherhood, the pattern was easily identified, it even annoyed me. Some of the events that occur felt rather predictable. In terms of being recognized as the superior Guild Master, this guild is definitely on top. Something happens in the questline that causes this to be very apparent. As time goes by, or maybe as you do side quests I can't really determine, you'll find initiates appearing randomly, which is pretty cool, and there's a lot of cool upgrades you can get for the hideout. After you've completed the contracts, the only thing there is left to do, however, is the radiant quests given by the Night Mother, you're sent to kill a certain person and you receive 600 gold upon completion. Sounds fun at first, but gets dull really quick. The rewards in general are okay, the weapons are the best part, but unfortunately of course, they scale to level.
I just felt in general that these quest lines weren't worth doing, if anything it's free achievement points, but I guess everything can't be perfect. What are your opinions on the subject?

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