Final Quilting Decision

I'm about to quilt the final section of the sky and I'm trying to decide what color of thread to use. Yesterday, I thought I was going to use ice blue thread, but today it isn't even a contender. Between the three colors shown, iris (darker purple), blue and amethyst (lighter purple), I'm leaning towards the iris. I think I'd like to darken up this area a bit and the purple would do that and add a little warmth. Which one do you like best?

I can't show you the whole quilt yet because it's going into an exhibit soon, but I bet you can guess what it is. Here's a close up of some of the quilting on my hand dyed fabric. Hope you can see it, the thread color blends pretty well.

I've been using my homemade pinmoor holders a lot and I absolutely love them. They stay in pretty well even through all the shifting, rolling and scrunching that you do while quilting, but they're easy to remove when you pull on the foam. I purchased extra pins and have about 120 now.