The darker turquoise for binding is all it needs.

If using a border white is the color to go with. You already have enough color

What an awesome quilt. I love the colors in your fabric. Just pick your favorite solid color from the top and go for it.

What is bag out?

I don't think it needs a border. As for the binding I might consider strips of the various stripes.
bc

Does it really need a border - it's pretty the way it is now. The colors are many, so any of them would make a nice binding color. If you just want a bigger quilt, a border in yellow or blue to match the quilt top would be pretty.

I would play around with several solid colors taken from the fabrics-- maybe 5 different colors/shades, distributed around the edges in such a way that the color makes the turn at the corners . I might even piece some interesting very thin strips of the striped fabrics into the border, maybe making an arrow effect chasing around the perimeter. And after I tried out those awesome ideas, I would probably decide to go with no border and I'd use the discarded border concepts to make coordinating throw pillows.

Was this my comment. Bag out. Right sides together with batting on top sew all the way around except for a small opening in one side. The opening is for turning the quilt from wrong side to right side through.
It's the only term I know for this method . Is there another.