Which colours should I offer?

[MusicallyChallenged]

2 boys, 2 girls.
Painting canvas which I will pre-paint with a single colour before they come to decorate it.
I have blue, green, metallic purple, orange, yellow and red.

My DD wants metallic purple and DS wants orange.

Torn between one of each and assuming all the girls will prefer shiny purple...

Can't you ask them?

I'd have chosen red or green.

Where will the canvases hang?
Maybe base the background colour on that.

No. Need to prepare them this morning, and they don't know what they'll be doing at the party.

They can take them home.

One of each, let them choose.

Yellow is a good background colour.