I carry 4 smaller bags - I am thinking about combining this all into an industrial backpack and having another backpack for recovery.
* Sockets every size in 3/8 - tekton kit
* Misc hand tools / with a breaker bar (with 19mm) and everything to change out a u-joint.
* Tire kit
* Electrical kit
Up until 3 years ago, I didn't have a garage at my house so my toolkit in the Jeep was huge since it was all my Jeep related tools. I do now carry a lot less and there are those odd times I saved the day by pulling out an air grinder or snap ring plyer with my old setup I can't do anymore but it was just too much weight.
I still struggle with how much/what fluid to carry. Diff fluid seems to be most used, then power steering but in all my years I've never needed brake fluid or engine oil but I often will carry.
I do carry a few other things:
Milwaukee chainsaw, recovery kit, change of clothes, toilet kit, coffee kit (includes small stove), 4L of water, battery booster that can also charge phones, outer stub, fan belt, chair, hand cleaner, jack stand, gloves, paper towel and a tarp.
If I'm going on a harder trail I'll throw in a few extra things
* electric impact
* power probe