Power Ring affiliation

I asked myself lots of times why some characters in DC wear a certain Power Ring while others who would fit in the same category not (of course storyline etc.). Wich characters in your opinion should get a power ring (by their display of the certain emotion) and what color?

and wich being would profit most of the "ring upgarde".

IMO:

Doomsday: Red
Amazo: Yellow
Superboy Prime: Yellow
Darkseid: Yellow

feel free to add Marvel characters aswell

Spider-man: Green
Dr. Doom: Yellow
Thanos: Yellow

Thanos:Green,Yellow or Black.
DD:Green.
Dr.Doom:Green or Yellow

WWH: Red
Wraith: Black

Professor X: Blue
Mister X: Orange
Juggernaut: Red

Doomsday: Red
Amazo: Orange
Superboy Prime: Yellow
Darkseid: Yellow
Spider-man: Green
Dr. Doom: Yellow
Thanos: Black
Professor X: Blue
Mister X: Black
Juggernaut: Red
WWH: Red
Wraith: Red
Dr.Light: Red

Thanos : black & ORANGE
Hulk : red
Rulk : red 😛