This is really the right answer here.
from OP: I’ll start with what I’m wanting it for.
I want the most reliable and capable option off road first and foremost: the 70 or 80 is pretty damn capable offroad, I don't buy that the 80 series will walk all over a 70 because it's leaf spring and leaf springs don't work as well offroad. hello
@RustyNailJustin and KOH on OG leaf springs. Slap some lockers and good tires and either rig will go farther offroad that most people want to take them...and both are big whales that are going to smash up the body if you are going that hard. Both can be really reliable once you baseline them...neither are "new"
I’ll most just be using it for overlanding but I want the“just in case option” you know? Again a wash. Which one do you like more? Which space fits you better. Both 4 doors are similar in cargo space, a troopy gives some more options. Coils will ride smoother, but you can get a decent leaf spring ride.
I plan to keep the car forever and I’m a bit paranoid so I want something for SHTF/Bugging Out. Either will be something you can keep forever and will survive as well as possible if the SHTF. Simple diesels have arguably less electronics...my BJ74 doesn't even need a battery to start/run. Bump it and go... no need to worry about EMP attacks here
I want as much cargo space as possible and I’m gonna need the backseat for the kids. Again, either will work, A troopy will have more configurable space inside and you can get more legroom in the back if you want.
It boils down to what you want honestly. Either are strong and reliable and awesome at offroading. Either will get you out of dodge.
70 or 80?
You WILL have to plan a little more for 70's parts, but it's not that hard/bad to deal with as I said plenty of vendors on mud have a bunch of non-usa parts. Other than that, IMO it's a wash for what you want to do with it.