Zealots Of The Nine Mod.
This mod adds a fairly big and complex quest to the Oblivion storyline. A secret society called the Zealots of the Nine form the pillar of the story. They are suppressing a group of worshippers, who follow the ancient Over Father. You start looking for a maid's employer, but soon uncover proof of this secret society and you will have to choose who to believe and who you will help.
Part of the quest line has a reward in the form of a new house. It's a mansion on the hill in Cheydinhal with a nice view over the river and the Cathedral. But there is more to be won than just the house. Can you get to the bottom of this conspiracy? Remember when you go into the dungeons, to bring plenty of potions and keep your senses sharp, there will be many surprises waiting for you in the dungeons.
Mod includes a new home, a mansion on the hill in Cheydinhal, overlooking the river and Cathedral. The home includes all the required amenities, and will provide a great base of operations. The home will become yours to use when you complete one of the included quest lines. The chests and other storage in the home will not re-spawn with items automatically, so your items will be safe.
I think one of the strong points of the mod is the fact that there are different ways of completing it. This brings it on the level of Bethesda's own mods, although some voice acting would have enhanced the experience further.