Kobo color vs Kindle Oasis in dark mode?

What's the difference between a color ereader and a b/w in dark mode? I'm thinking of getting a kobo color model and wondering if I can switch from b/w (Kindle Oasis). I only read in dark mode; I'm astigmatic and find dark mode easier to read without glasses. Now I'm so used to it I just prefer dark mode all the time. Could some kind person tell me what they think and even take side by side photos of color vs b/w, both in dark mode? Is the contrast better or worse? Thank you!