updated April 28th, 2017
Oblivion's Gameplay is a step up and step down from Morrowind. Lets fix that.
In this section, we will discuss:
Big mod packs that add a whole slew of new content as well as major tweaks to make Oblivion a lot more fun to play.
Francesco's and Martigen's overhauls can work together with a few compatiblity patches, but to get all of these overhauls to work together, you're going to need to the mother of all overhauls; FCOM.
There are also a few newer Oblivion overhauls that aren't compatible with FCOM but are just as good standalone.
Oscuros Oblivion Overhaul
OOO - This is THE overhaul mod when someone talks about Oblivion overhauls. Being one of the biggest and one of the best overhauls for Oblivion, itt tweaks everything from enemy AI to loot drops and adds more content such as new enemies, items, and much more! Also be sure to download the equipment add-on for OOO.
FCOM: Convergence may sound like it's own game in itself, but it's actually the biggest overhaul mod for Oblivion because it combines all of the overhaul mods listed above, and then some, into one big clusterfuck. It combines Oscuro's Oblivion Overhaul, Martigen's Monster Mod, Oblivion WarCry, and Francesco's Leveled Creatures-Items together as well as a bunch of smaller overhauls and weapon packs. If you have a lot of free time on your hands and are ballsy enough to do it, then go right ahead and attempt to install the largest and most complicated overhaul mod ever. Godspeed to you.
Alternative Start Arrive by ShipGo on a ship to go to a place and choose who you are while on the ship. Sound familiar? It should.
Supreme Magicka UpdateThis mod overhauls the magic system of Oblivion to create a more balanced, diverse, and fun system. It adds new effects, new spells, and more in order to enhance the game for mages and anyone else who thinks magic is too weak.
Enhanced EconomyEnhanced Economy is a complete overhaul of Oblivion's economic game, tweaking how haggling works and how money work entirely. You can make edits to local and global economies as well as calculate how your mercantile skill will effect costs.
Midas Magic Spells of AurumThe best magic mod for Oblivion. Midas adds over 300 unique spells that are a mix between funny and plain old overpowered.
Vanilla Combat EnhancedTweaks all the ins and outs of vanilla combat and is easily customizable by adjusting the ini files.
More Effective EnchantmentsThis addon fixes the extremely limited amount of uses on enchanted weapons (including staves). By default the amount of uses is multiplied by 5. Through OMOD installation and/or by editing the .ini file this amount can be modified.
Archery RebalanceArchery in vanilla oblivion was mostly a tedious work of running backwards while shooting arrows into enemies chasing you at full speed with arrows sticking out of every body part. This mod increases arrow damage enough to make archery useful and shooting an arrow is no longer like throwing a stone, arrows goes much faster and straighter!