I ended up going with black. Didn't really feel there was another option. Actually bought a green mini and was gonna sell my red one, but returned it lol. Plus, to break even money-wise I would've had to downgrade from 512gb on my red to 256gb on the green.
Do you still use your mini and your black case?
I kind of have the same problem, nothing looks really good with red. And yet I think the red is my favourite colour (I do also like the green one a lot).
So I got myself a transparent case. Haven't tested it yet because I'm thinking of returning the red phone because I'm scared nothing will fit with it, and don't want to open it yet.
What I like the least is the combo red/black though. It just looks evil. And my problem is, when facing the phone, the screen will be black, but the border will be red. I'm not sure if my clear case will cover this. This part is bother me the most 🤣
The back with the clear case would surely look amazing though.