SH5 is a lot more immersive to me than SH4.
Have both installed on computer, and i didn't run SH4 for long time now...
Furthermore, Pacific is way too big
In SH5 i love the way we can move into the sub, i love the sea/clouds/sun rendering once mods activated, i love all the sounds given by modders, all the awesome details everywhere, and i love the way it's so hard if we want to!
Have yet to try the unique real navigation feature that only exist in SH5.
But game is enough hard for me at the moment
+ OHII Full is the best campaign i have ever done.