Is there such a thing as too many armour mods?

Adonnays Classical Weaponry-9185 [Classical Weaponry v070 - OBSE]
Adonnays Elven Longblades-5024
Adonnays Elven Weaponry-4804 [Elven Weaponry 375 full final]
Adonnays Ranger Coats-12641
Akaviri Imports-4167
Alternative Glass Armor Pack-3187
Andragorns weapons and armors-26490
Apophis Armory of the Silver Dragon-8440
ArmamentariumComplete_ver_1_35-18417
Ayleid Meteoric Iron Weaponry Now With Revamped Models and T-5521[Already part of OOO 1.3+]
Dopplers Armory-17492
FB - Dark Crusader Mega Pack OMOD-32393
Female Armor Pack OMOD-4362
FineWeapons-PyFFI-7317.7z
Frostmourne and Lich Kings Armor-17032
Gizmodians Blades[5]
Insanity's Improved Armoury Compilation 1.1-TESA
Kafeis Armored Circlets-10670
KnightlyArmory-19228
Lost Paladins of the Divines-10505
Lost Paladins of the Divines Add on replacement pack-31063
Lost Paladins of the Divines v2
Loths Blunt Weapons-12939
Myths and Legends Weapons 2-5902
Natures Arsenal for Rangers Druids etc-26478
Nexons Armory-31340
Nicoroshi Creations-13519 16 October 2007
+Nicos Kynareth Archery v1_0-19096
+Nicos Scimitars-16204
+Nicos Tabaxi Bows-17444
+Wyrmfang-14641
Phinix Dual-Wielding Imports-33170
Phitts Helmet Collection-8628
RuneSkulls-9412[250]
Sentinel Legendary Weapons And Armors-36954
tda Armoury-25332
Unofficial Francescos Mod Armor AddOn-11483
Vvardenfell Imports-28245[Many]
Vvardenfell Imports Addon-28246[30]
*Weapon Expansion Pack for Oblivion Nthusiasts-35560
WeaponsOfTheNine2.2FULL-7013

Only if you try and use every single one of them at the same time, I have a hard time choosing from my selection of armor mods too.
No collection of armor mods will ever be complete, I always find a new one I have to try.

I'm going to have to figure out which ones conflict the least, if any and which ones have the biggest impact.

Most armor and weapon mods cause very few conflicts, but compilations that add a building to the game can require patches, especially when using mods like Better Cities and OCC/OCR, and Unique Landscapes.
If you use FCOM, some of your armor mods are included in it (meshes and textures at least). I know Addonays Classical Weaponry can make a part of an OOO quest near Bruma very easy.<--- I can answer more specifically via PM because this is a spoiler
There is a fixed version of the Frostmourne Sword, the original can cause a CTD when the sword was sheathed/unsheathed because of a script.
BOSS can also point out some specific conflicts, WEPON does conflict with a few modded weapon sets because of what it is and how it works.

My first play through was based on MMM. This time I'm going to try OOO. I will probably use some combination of:

ArmamentariumComplete1.35
Weapon Expansion Pack for Oblivion Nthusiasts-35560
Lost Paladins of the Divines
Vvardenfell Imports-28245
Insanity's Improved Armoury Compilation 1.1-TESA

What does WEPON conflict with?

WEPON conflicts with other weapon sets that are used with OOO one of which is Fine Weapons, because WEPON fills in the same kinds of gaps in the Vanilla weapon assortments, Rusty Items and Mithril and Orcish Weapons Sets v1 and v2 are the others.

I've been trying to combine armor-weapon mods for my own personal use, because there are too many good mods out there to sacrifice a space on my load order for one or two tiny armor/weapon mods. But... turns out its a little harder than I first thought. :confused:

Maybe I will try loading it before OOO.

WEPON does not conflict with OOO by itself, it just conflicts with mods that are often used with an OOO/FCOM mod setup, I just copied the names from my BOSSlog. I did recognise Fine Weapons from your list.

Did you try merging them with TESGecko?

Well, yes, but once you do that, you want to make sure they're balanced and in the leveled lists, which takes time and energy. And adding things to the leveled lists isn't something I've really mastered yet, and balancing is difficult at any level. Especially if you have mods that alter the stats of weapons and armor, which you have to take into account when balancing your added-in weapons and armor.