My friend has had a Kia EV6 for three years now, and the battery's holding at around 95% of its rated capacity - that's normal for that age. Korean manufacturers really have stepped up their game over the last 5-7 years, and it's especially noticeable with EVs since there are just fewer moving parts and things to break.
The ID.4 is a proven platform, but Germans have this one quirk: they love overcomplicating the electronics. When something breaks down, the diagnostics at the service center can drag on forever. The Geometry C Plus - I wouldn't really consider it in that price range. Sure, Chinese batteries have improved, but the long-term reliability stats just aren't as convincing as you'd want them to be. Plus there can be issues with warranty coverage once you're outside the official dealer network.
Between your options, I'd go with the EV6: the reliability margin is about 10-15% higher, and the battery degrades more slowly in real-world conditions. The ID.4 is also a solid choice, but if the warranty isn't full coverage anymore, you should budget some reserve for electronics. The EV6 is more reassuring in that respect, even after the first 100,000 km.