I'd keep it simple and not take away from the focuse of the main part of the block. What you have, then a narrow white, then a wider border of the turquoise and bind in the turquoise.

Take the bright blue away (the inside border) and carry on with the white border and blue cornerstones. That will 'finish' the center of the quilt. Then use one of the colours from the center squares for final border. You could bind it with strips from all the fabrics in the squares.

ITA ... partly!
Missed that ... yes finish the white and blue cornerstones. Then a wide blue border the same same width of th blocks.

Yes, I agree, and for the border use the yellow background which is in the centre block in the second row down. Then use any one or more of the darkest colours for the binding.

Are you confused yet with too many suggestions?

i'd use the blue fabric with the multicoloured hearts if you have enough.

I almost didn't even notice the yellow border it's showing up so pale. The blocks are nice and bright - think you need a border with more pizzaz.

cut the block fabrics into uneven rectangles [4inches or 6] and join them together what you have spoils the great blocks

I agree that you need something there with a little more punch.Something with a spot or two of your brighter colors.Sorry I can't agree with what you have.

I still favor replacing that "dull" border with a splashy, colorful print! Very, very nice!

I didn't even see the light yellow print. I thought it was something you put your quilt on to take a picture. Personally, I think it looks great with the bright blue border and white corners. I'd stop there unless it needs to be bigger.