So, I've been looking at the results and I have to say I'm happy that people are expressing their thoughts. I think it's about time to express my opinion.
I believe that the character has to be the best at what they do in order to rise through the ranks. For example, if I'm in the Mages guild, I should be actively competing with other members of the faction for a promotion. This is lacking in TES games in my opinion. You do what you're supposed to do to advance, but no matter how slowly or quickly you finish your assignment, you still end up advancing in the end. There should be some form of candidacy, where you have to fight others for the favor of your superiors.
Despite the constant criticism Oblivion gets, I feel like Oblivion's factions were more interesting to a degree. For example, the Morag Tong in Morrowind involved killing people, and eventually killing members of the Dark Brotherhood before becoming Grand Master. On the other hand, the Dark Brotherhood in Oblivion involved not just killing people, but killing them in interesting ways, like assassinating people one by one in a building without the others knowing, or poisoning a sick warlord in his sleep. And this was all tied up with a plot where the PC is used as a tool to tear the Brotherhood apart from the inside.
But the factions in Oblivion were also smaller, and shorter. My favorite faction in Morrowind, the Imperial Cult, designed specifically for alchemists/healers, was absent in Oblivion. Therefore, I believe that factions should play a greater role in future ES titles. Factions should be more numerous (because I want to see a Healer faction), more varied (contain political parties, perhaps), and should have plots that make being in the faction worthwhile. Along with improvements to advancement (I believe that skill requirements should return to prevent speeding through the factions), the factions in ESV would definitely be incredible. But seeing that Bethesda's project is so far along in development, we'll just have to wait and see.