Which color was the most iconic for the Game Boy Color?

Purple, no contest. Both solid and see-through.

Opaque purple is used by Nintendo for Virtual Console and in most ads for GBC games. Meanwhile, is there anything that screams "90s handheld gaming" more than the translucent purple one?
Man, I was so embarrassed to get this for Christmas. I ended up covering it in black electrical tape at some point because I didn't want to be seen holding a Pokemon GameBoy.

RIP see through OG GameBoy.
Are you kidding? I loved my Pokemon Yellow GBC. I thought that was the best looking one. I agree with the consensus though that Atomic Purple is the "definitive" color.
I had the normal purple one, my friend had the limegreen one that looked so much better.

We exchanged Pokémons via that cable thing, and somehow he lost his save file during that and didn't speak to me for like 2 weeks.
First one I thought of was lime green, which is weird because I never had one? It's definitely the solid purple one though, followed closely by the transparent purple (which is the one I had). I remember the GBC was my first time ever being truly impressed by how attractive a device could be, though in retrospect I was just too young to fully appreciate the aesthetically superior Game Boy Pocket.
I love my yellow one, but everyone else I grew up with had atomic purple.

I also had an "extreme green" see-through Game Boy Pocket. Played a ton of Mario Land, Wario Land, and Tetris. ^-^
At launch they only had atomic purple and purple, at least in Europe. All other colors (and the Pokèmon yellow version) came out slightly after.