A leveling mod that rids the game of the vanilla attribute chase, followed by one that lets me control the pace at which I level skills come at the top of my list. Like many others I find an ngcd + Progress setup fills that void ideally.
The addition of some personal mods and tweaking is also something I've done to create longevity.
And I wouldn't dream of playing without FCOM.
I've also found that adjusting the difficulty slider as you move into the higher levels increases the challenge, otherwise the tendency is for your avatar to outgrow your mods.
At 30 plus I run the game normally at 75/85%. Any higher and it's instant death when facing two or more ranged attackers.
To give you some ideas for additions my mod list -
Spoiler Active Mod Files:
00 Oblivion.esm
01 All Natural Base.esm [Version 1.3]
02 Francesco's Leveled Creatures-Items Mod.esm [Version 4.5bSI]
03 Francesco's Optional New Items Add-On.esm [Version 4.5bSI]
04 Cobl Main.esm [Version 1.73]
05 TamRes.esm
06 Oscuro's_Oblivion_Overhaul.esm [Version 1.35Alpha2]
07 Mart's Monster Mod.esm [Version 3.8b1]
08 FCOM_Convergence.esm [Version 0.9.9MB8b1]
09 Progress.esm [Version 2.2]
** Cobl Races TNR.esp [Version 1.53]
** Cobl Races TNR SI.esp [Version 1.53]
0A Unofficial Oblivion Patch.esp [Version 3.2.0]
0B DLCShiveringIsles.esp
0C Unofficial Shivering Isles Patch.esp [Version 1.4.0]
0D TamRes.esp
0E Francesco's Optional Chance of Stronger Bosses.esp
0F Francesco's Optional Chance of Stronger Enemies.esp
10 Francesco's Optional Chance of More Enemies.esp
11 Francesco's Optional Leveled Guards.esp
++ FCOM_Francescos.esp [Version 0.9.9MB8b1]
++ FCOM_FrancescosItemsAddOn.esp [Version 0.9.9MB8b1]
12 FCOM_FrancescosNamedBosses.esp [Version 0.9.9MB8b1]
13 Fran_Lv30Item_Maltz.esp
++ LoadingScreens.esp
14 LoadingScreensAddOn.esp
** LoadingScreensSI.esp
15 Natural Selection.esp [Version 1.0]
16 All Natural.esp [Version 1.3]
17 All Natural - SI.esp [Version 1.3]
++ All Natural - MMM Patch.esp [Version 1.3]
18 Immersive Interiors.esp [Version 0.8]
19 Immersive Interiors - Lights Addon.esp [Version 0.8]
1A Realistic Water.esp
++ Symphony of Violence.esp
1B MIS.esp
1C MIS New Sounds Optional Part.esp
1D Atmospheric Oblivion.esp
1E All Natural - Real Lights.esp [Version 1.3]
1F WindowLightingSystem.esp
20 AFK_PrayerIdles.esp [Version 1.0]
21 Book Jackets Oblivion.esp
22 ImprovedSigns.esp
23 RAEVWD Cities.esp [Version 1.9]
24 RAEVWD New Sheoth.esp [Version 1.7]
25 RAEVWD Imperial City.esp [Version 1.9]
++ VA_BetterGold.esp
26 Willful Resistance.esp [Version 4.0]
27 Enhanced Seasons.esp [Version 1.3.1]
28 Enhanced Economy non format.esp
29 Streamline 3.1.esp
2A Map Marker Overhaul.esp [Version 3.8]
2B Map Marker Overhaul - SI additions.esp [Version 3.5]
2C Landmarks, w Wells.esp [Version 1.11]
2D MapMarkers.esp
2E Expanded Hotkeys and Spell Delete V2.esp
2F DLCMehrunesRazor.esp
30 DLCMehrunesRazor - Unofficial Patch.esp [Version 1.0.4]
31 ExnemEyeCandy.esp
++ MaleBodyReplacerV4.esp
32 Adonnays Classical Weaponry.esp
33 Reznod_Mannequin_HD[Eng].esp
++ RustyItems for OOO.esp
34 tda_Armoury Beta v1_2.esp
** StockClothingArmor-forExnems.esp
++ Restoration.esp
35 Cobl Glue.esp [Version 1.73]
36 Cobl Si.esp [Version 1.63]
37 Bob's Armory Oblivion.esp
38 FCOM_BobsArmory.esp [Version 0.9.9]
39 Loth's Blunt Weapons for Npcs.esp
++ FCOM_LothsBluntWeapons.esp [Version 0.9.9]
3A Oblivion WarCry EV.esp [Version 1.09]
3B FCOM_WarCry.esp [Version 0.9.9MB8b1]
3C Oscuro's_Oblivion_Overhaul.esp [Version 1.35Alpha2]
3D Alluring Potion Bottles v3.esp
3E Alluring Wine Bottles.esp
** OMOBS_SI.esp [Version 2.0]
3F OOO 1.32-Cobl.esp [Version 1.72]
40 Mart's Monster Mod - Additional Enemy NPC Vars.esp [Version 3.8b1]
41 FCOM_Convergence.esp [Version 0.9.9Mb8b1]
++ FCOM_EntropicOrderRebalance.esp [Version 0.9.9beta2]
42 FCOM_RealSwords.esp [Version 0.9.9MB8]
++ FCOM_SpawnRatesStronger.esp [Version 0.9.9Mb3]
43 Mart's Monster Mod - More Wilderness Life.esp [Version 3.8b1]
++ Mart's Monster Mod - More Passive Wildlife.esp [Version 3.8b1]
++ FCOM_LessRats.esp [Version 0.9.9]
++ Mart's Monster Mod - No Pests.esp [Version 3.8b1]
++ Mart's Monster Mod - No Swarms.esp [Version 3.8b1]
++ FCOM_NoReaversInGates.esp [Version 0.9.9]
++ FCOM_NoAdventurersInGates.esp [Version 0.9.9]
44 Mart's Monster Mod - Extra Wounding.esp [Version 3.8b1]
45 Mart's Monster Mod - No Carrion Rats.esp [Version 3.8b1]
++ Mart's Monster Mod - No Bone Loot.esp [Version 3.8b1]
++ Mart's Monster Mod - No Slimes.esp [Version 3.8b1]
++ Mart's Monster Mod - No Fiends.esp [Version 3.8b1]
++ Mart's Monster Mod - No Werewolves.esp [Version 3.8b1]
++ Mart's Monster Mod - No Beholdens.esp [Version 3.8b1]
++ Mart's Monster Mod - No Uberhulks.esp [Version 3.8b1]
++ Mart's Monster Mod - No Skeep.esp [Version 3.8b1]
46 Mart's Monster Mod - Zombies for Body Meshes.esp [Version 3.8b1]
47 Mart's Monster Mod - Farm Animals.esp [Version 3.8b1]
++ Mart's Monster Mod - Slof Horses Complete.esp [Version 3.8b1]
++ Mart's Monster Mod - Diverse Runeskulls Loot OOO.esp [Version 3.8b1]
** FCOM_FriendlierFactions.esp [Version 0.9.9]
++ Mart's Monster Mod - Shivering Isles.esp [Version 3.8b1]
++ FCOM_HungersUnitySI.esp [Version 0.9.9MB8b1]
++ Atmospheric Oblivion - MMM Patch.esp
++ Atmospheric Oblivion - OOO Patch.esp
++ StockClothingArmor-forExnems - OOO Patch.esp
++ MMM-Cobl.esp [Version 1.73]
48 CNRP Bruma4OOO.esp [Version 0.2]
49 CNRP Chorrol4OOO.esp [Version 1.1]
4A CNRP Cheydinhal4OOO.esp [Version 1.0]
4B CNRP FightersGuild4OOO.esp [Version 1.0]
4C Ivellon.esp [Version 1.8]
4D 300_Artifacts.esp
4E AdenseEpicDungeon.esp
4F allinonebasemant_COBLnoCM.esp
50 Imperial Furniture Renovated.esp
51 Basemant_chorrolhouse.esp
52 Bruma_House__Fireplace_with_Fire-2800.esp
53 Deathtrap Dungeon.esp
54 LostSwordOfTheAylied.esp
55 Muffin Display Rooms.esp
56 TheWellOfMinlorada.esp
57 The Ayleid Steps.esp [Version 3.4]
58 TheForgottenShields.esp
59 WOTFH_1.3.esp
5A Knights.esp
5B Knights - Unofficial Patch.esp [Version 1.0.9]
5C The Lost Spires.esp
5D GuardsofCyrodiilRedux.esp [Version 1.12]
5E Lost Paladins of the Divines.esp
5F HoarfrostCastle.esp
60 MannimarcoRevisited.esp
61 MannimarcoRevisitedOOO.esp [Version 0.1]
++ FCOM_Knights.esp [Version 0.9.9MB8b1]
62 xuldarkforest.esp [Version 1.0.5]
63 LostSpires-DarkForest patch.esp
64 xulStendarrValley.esp [Version 1.2.2]
65 xulTheHeath.esp
66 MMMMWL-TheHeath patch.esp
67 XulEntiusGorge.esp
68 xulFallenleafEverglade.esp [Version 1.3.1]
69 LostSpires-Everglade patch.esp
6A xulColovianHighlands_EV.esp [Version 1.2.1]
6B xulChorrolHinterland.esp [Version 1.2.2]
6C xulBeachesOfCyrodiilLostCoast.esp [Version 1.6.4]
6D xulBravilBarrowfields.esp [Version 1.3.2]
6E LostSpires-BravilBarrowfields patch.esp
6F xulLushWoodlands.esp [Version 1.3.1]
70 HoarfrostCastle-LushWoodlands patch.esp
71 xulAncientYews.esp [Version 1.4.3]
72 xulAncientRedwoods.esp [Version 1.6]
73 xulCloudtopMountains.esp [Version 1.0.3]
74 xulArriusCreek.esp [Version 1.1.3]
75 xulPatch_AY_AC.esp [Version 1.1]
76 MMMMWL-RollingHills patch.esp
77 xulPantherRiver.esp
78 xulRiverEthe.esp [Version 1.0.2]
79 xulBrenaRiverRavine.esp [Version 1.1]
7A xulImperialIsle.esp [Version 1.6.6]
7B UL Imperial Isle Adense Epic Dungeon Patch.esp
7C xulBlackwoodForest.esp [Version 1.1.0]
7D xulCheydinhalFalls.esp [Version 1.0.1]
7E DungeonsOfIvellon-CheydinhalFalls patch.esp
7F xulAspenWood.esp [Version 1.0.2]
80 xulSkingradOutskirts.esp [Version 1.0.1]
81 xulSnowdale.esp [Version 1.0.2]
82 OOO-Snowdale Patch.esp
83 xulCliffsOfAnvil.esp
84 OOOCliffsofAnvilPatch.esp [Version 1.1]
85 xulSilverfishRiverValley.esp [Version 1.0]
86 Lost Spires + Silverfish River Patch.esp [Version 1.0]
87 Fort Akatosh Redux.esp
++ Cyrodiil Legion Addon.esp [Version 1.3]
88 Legion Ranger Addon.esp
89 Harvest [Flora].esp [Version 3.0.0]
++ Harvest [Flora] - Shivering Isles.esp [Version 3.0.0]
8A DZ_Auto_Harvest.esp
++ Visually Realistic Deadly Lava.esp
8B AutoBookPlacer.esp [Version 3.02]
8C Birthsigns Expanded.esp [Version 3.21.]
8D DecoratorAssistant with OBSE v1.1.esp
8E Dungeon Actors Have Torches 1.6 CT.esp
8F Exterior Actors Have Torches 1.3 CT.esp
90 Reset Your Status Page.esp [Version 0.0.8]
91 Speedy Disrobe OBSE.esp [Version 1.3]
92 Quest Award Leveller.esp [Version 2.0.1]
++ Quest Award Leveller - Mehrunes Razor.esp [Version 2.1.0]
93 Quest Award Leveller - Knights of the Nine.esp [Version 2.1.0]
94 Alchemy nerf.esp
++ EnchantmentFixes/recharge.esp
95 Advanced Mark & Recall.esp
96 SetEssentialActors.esp
97 Smite of Order.esp
++ Illusion fix.esp
98 AgarMoreVariedSpellEffects.esp
99 SSEE-OOO.esp
9A Armorer's Advantage.esp
9B nGCD.esp
++ nGCD Skeleton Key.esp
9C ProgressGSD.esp [Version 2.0]
9D ProgressMBSP.esp [Version 2.0]
9E ProgressSBSP.esp [Version 1.0]
9F ProgressRacial.esp
A0 ProgressArmorer.esp [Version 1.0]
++ Immediate Character Generation.esp
A1 The Versatile Adventurer.esp
++ DMC Stylish - Specialanims.esp
** Cava Obscura - Cyrodiil.esp
** Cava Obscura - SI.esp
** Cava Obscura - Filter Patch For Mods.esp
++ Mart's Monster Mod - Resized Races.esp [Version 3.8b1]
A2 ZUAmberMadnessOverhaul.esp
A3 ZUSIO-RatsInCrucible.esp
++ ZUSIO-MMM SI-patch.esp
A4 ZUSIO-Map MarkerOverhaul SI-patch.esp
A5 No More Annoying Comments.esp
** [GFX]_Initial_Glow-all.esp
++ X-Ray Detect.esp
A6 Cobl Silent Equip Misc.esp [Version 01]
A7 Mart's Monster Mod - Diverse Creatures Expansion.esp [Version 3.8b1]
A8 MMM Mummy.esp
A9 Gift of Kynareth.esp
AA GiftOfKynareth-CheydinhalFalls patch.esp
AB Cobl Races.esp [Version 1.52]
AC Cobl Variations.esp
++ DiverseDremoraArmorFCOM.esp
** All Natural - Indoor Weather Filter For Mods.esp [Version 1.3]
++ Oscuro's_Oblivion_Overhaul - Harvest Containers - SI.esp [Version 0.99b]
++ Cobl Filter Late MERGE ONLY.esp [Version 1.53]
AD Bashed Patch, 3.esp
Note that the version of FCOM and many associated plug-ins are
not available for general download, as are some other esp's shown which are my own personal game tweaks and fixes, so don't be asking for a download link or searching google for them.
I hope this gives you a general idea for a game build.
Good luck