First ending I did was Johnnys way and Judy leave at the end plus the, obvious, place of glory suicide in space were a really depressing ending of 50 hours of game time.
I do concure with most of what is said here but I have a slightly different thought about the Soulkiller.
It does kill V, yes, however Soulkiller is meant to copy the mind of the host to transfer it to the Relic / Mikoshi, or a new body ( yes, looking at you Saburo), which give it its name as it does not copy ones soul.
Now if we think in technical ways, its the similar as to copying an operating system to a new machine. To do so the running system has to be stopped, or suspended ( flatlined V ), to have access to one fixed state of it and not having to deal with ongoing thought processes or memories being formed.
If V decides to return to their body its not a new body, its still the original and their old mind / brain is still there, just suspended by the Soulkiller processes. Alt uploads the engram to the cybernatic part and may that what the nanites had affected, thus V knows what had transpired in Mikoshi, and reanimates the body again thus restarting the brain as well, just like the nanites did when Dex shot them.
Given this it does shine a different light on the endings based on what Hellman says during the Arisaka ending "Well, you don't have a whole team and facility dedicated to just you.", meaning that there would be a possible way to fix the damage of the Relic if they would want to.
So based on that the endings feel like:
Suicide = End of the line.
All Johnny take over = Basicly the same as suicide for V, not sure if I should feel happy for Johnny to get a new chance, one which he didn't really deserves.
Arisaka Ending = They don't want to spend money on V, thus going the easy way of offering to store them on Mikoshi or sending them off as a vegetable.
Johnnys Way / Fear the Reaper = Though V may have a romance (if you choose to) at their side they are still alone and stuck in their old ways, possibly blind to other options too as they are still the Lone Wolf. They have lots of money and connection but noone is really supporting their search and Night City is a dead end as Arisaka is left in ruins.
Panam = V is no longer alone, not the Lone Wolf caged in a city of neon anymore. Its one of the reasons Atlanta (Streetkid) or Arisaka Security (Corpo) didn't work, V had noone there either. They have a family now, a close and supporting friend (possibly their romance option at their side) plus all the nomands connections outside the city. Going back on Hellmans remark, here V has one of the 2 requirements to survive already, and from ingame commentaries and the
Cyberpunk Wiki a very good bet for the 2nd would be the medical facilities in Sweden.