>Iron Blood Orphans is probably the most 'realistic' in the genre.
Save Barbatos' waist circumference. /s Joking aside, while it still succumbs to a lot of genre and franchise cliches, I have to agree that it did a lot of things more maturely than preceding series. The ending is one of the most refreshingly grounded in the franchise (which is probably why so many fans hate it).
Operation British in MSG started a strange trend where Australia gets left with large crater marks in basically every Gundam timeline, and many non-Gundam properties.
The whole colony drop scene in MSG just terrified me as a kid. It was the first time I saw large scale human-on-human violence expressed in such a medium, and I was not ready for it. Then I realized "oh, this is a metaphor for the US nuking Japan".
Warning: it's rough and not a happy series.