My suggestion is to pick a few at a time, some do indeed conflict. The
Oblivion Mod Manager and
Oblivion Script Extender are musts for many of the mods - get them. OMM includes a feature for finding conflicts.
My favorites are Clocks of Cyrodil - which adds working clocks to the game. Not all that useful, or plot heavy, but I think they are neat. The Unique Landscapes series of mods are another that do not change game play, but if you have a tendency to play tourist (like I do) they are wonderful. However, they are also the most likely to cause conflicts, or at least some odd problems, like castles floating in the air because the elevations have been changed. Not a problem with the core buildings, but other mods can suffer.
One that changes the game, but only after part of the main quest is completed is the Kvatch Aftermath mod - the town gets rebuilt, and a bunch of quests, buildings, and NPCs are added to the game.
Though it hasn't been updated since July
this is a great place to start - but I warn you, many of the links became broken when the source he referred to most changed URLs. Look for the titles at
TesNexus instead.
And I am a huge fan of
Oblivion Real Estate a site dedicated to buildings and the creation of such for the game. (Again, I like having nice looking terrain....) Lots of really nice buildings, though the most
useful is Bond's Big Portable Tent - a house (well, tent) you can fold up and carry with you - but it is
heavy. (Which helps balance the extreme usefulness. Being able to hole up when you want to level is a huge advantage.) Plus you need plenty of room to pitch your tent. Less useful, but one of the niftiest (if somewhat kludgy) mods out there is the Bella Moretta - a fully functional ship. This suffers from conflicts with several mods that use the same dock that she is tied up to - including one official expansion to the game.
For quests
this is quite possibly the best site - my favorite is Knights of the White Stallion, which builds on the Mazoga the would be knight quest in the main game. It turns the story into a small war. My reason? I like Mazoga.
And a site with mods that
'Shouldn't Have Been Mods' - mods that the writer feels should have been part of the game itself.
Hope this all helps.
The Auld Grump
*EDIT* Added a few specifics.
