I am probably the wrong person to ask, since I think that pretty much every mod I have installed (190 mods), fits perfectly with the universe. Although, realistically, hidden within that content is no doubt exceptions.
I would ask, what oblivion mods DON'T feel cohesive.
G-Strings that grant a 1 or more armor rating
Everyone having ginormous briasts
lightsabers
machine guns
NPCs of certain races that speak perfect English.
Obviously wrong, or made up lore
Any mods that add stuff like Sephiroth and Chocobos
references and phrases not present in the game's world (like someone one saying: "Oh my God!", or meantiong earth and othersuch mistakes like that)
Modern architecture
etc.
With a lot of these you can get away with it by making it right, having it be a subtle joke or pop culture reference(For an example of how
not to be subtle look at Kragenier's Death Quest.), and/or by using the excuse of: "Dewemer/Sheogorath/Magic/alternate universe did it." Like guns and Flying ships can exist if properly integrated into the lore by Dwemer-izing them. (ie: steam punk type guns and ships)
but, yeah... most mods aren't completely crazy to the point of detracting from the game... I have seen some pretty lame stuff though. Like replacing most of the dungeon enemies with half naked women, quest mods starting with big rants by the mod authors, quest mods starting with screwing up your weather and giving some lame credits scene, the immediate pop-ups that even bethesda did... can't think of much else. I usually only take chances and try to give unknown mods a chance when it comes to quest mods, I'm a little more careful with gameplay mods.
Anyway my generic copy/paste has my general suggestions and stuff and none of it is stuff like that:
Spoiler
List of lists:
http://www.gamesas.com/index.php?showtopic=1010109
Top 100
http://www.tesnexus.com/downloads/top/alltime.php
Files of the months:
http://www.tesnexus.com/downloads/filesofthemonth.php
Hall of fame:
http://planetelderscrolls.gamespy.com/View.php?view=oblivionmods.HOF
http://www.tesnexus.com/downloads/categories.php, http://www.tesnexus.com/downloads/tags/search.php, http://www.tesnexus.com/downloads/advancedsearch.php
http://tesivpositive.animolious.com/
List of topics exactly like yours that have already been answered:
http://www.gamesas.com/index.php?/topic/1072579-the-any-mods-list-of-topics/
Read the AZERessential topics to get the basic "get wryebash, OBMM, OBSE, start slow" basic advice for starters recommendations
If you want any further help I suggest you tell us about yourself; what you like and what you're looking for... Here's some questions to get you started:
Have you played Oblivion already?
What sort of things interest you?
What type of Character do you usually play? (good/evil, theif/mage, roleplayer/random-no-story-hack-and-slasher?)
Are there specific types of mods you think would interest you? (Quests, graphic mods, gameplay mods, overhauls, etc.)
When did you leave?
What did you not like about Oblivion? What did Oblivion not have or need more of?
Male or female character?
For the occasional "What are your must haves?" Mostly quest mods: http://kno.li/i
My favorite quests are:
http://theelderscrolls.info/?go=dlfile&fileid=349 (my most favorite)
http://www.tesnexus.com/modules/members/index.php?id=125368
http://www.tesnexus.com/downloads/file.php?id=21989
http://www.tesnexus.com/downloads/file.php?id=17448
http://www.tesnexus.com/downloads/file.php?id=6977
http://www.tesnexus.com/downloads/file.php?id=6855
Ihttp://www.tesnexus.com/downloads/file.php?id=19591
[b]Gameplay mods:
http://www.tesnexus.com/downloads/file.php?id=25462
http://www.tesnexus.com/downloads/file.php?id=25835
http://www.tesnexus.com/downloads/file.php?id=22894
http://www.tesnexus.com/downloads/file.php?id=25844
http://www.tesnexus.com/downloads/file.php?id=25844
http://www.tesnexus.com/downloads/file.php?id=26196
http://www.tesnexus.com/downloads/file.php?id=18442
http://www.tesnexus.com/downloads/file.php?id=3409
http://www.tesnexus.com/downloads/file.php?id=21862(good for troubleshooting)
http://www.tesnexus.com/downloads/file.php?id=20736
http://www.tesnexus.com/downloads/file.php?id=20807
http://www.tesnexus.com/downloads/file.php?id=20371 (Needed for Integration)
http://www.tesnexus.com/downloads/file.php?id=22124 (Needed for Integration)
I'm mostly a quest mod player and I recently posted a big rundown for most of them that I've playedhttp://thenexusforums.com/index.php?s=&showtopic=157600&view=findpost&p=1349075 and http://www.gamefaqs.com/boards/genmessage.php?board=924363&topic=51137901.
(Some of these are probably outdated by now)
http://www.gamesas.com/index.php?act=findpost&pid=15598757
http://www.gamesas.com/bgsforums/index.php?s=&showtopic=1073167&view=findpost&p=15603156
http://www.gamesas.com/bgsforums/index.php?s=&showtopic=1073167&view=findpost&p=15602927 (Don't really want a lot top 10's or simple lists but I'm desperate for cop/pastes at the moment)
http://www.gamesas.com/bgsforums/index.php?s=&showtopic=1075680&view=findpost&p=15650213