Which came first the yarn or the project?

After finishing Charlott's Daughter's Shawl, Joy, I am really interested in knitting another lace shawl. I've been taking a lot of time with this choice. It's very serious. I did targeted searches on Ravelry, went through all my collected patterns, and had a discussion with Danni(our resident lace expert). The three yarns in the running are...

.Superior, a sport weight yarn that is a cashmere-silk blend.

Serenknitty, a fingering weight merino-seacell blend.

and Lobster Pot Cashmere laceweight yarn.

These are the patterns in the running:
1. Swallowtail shawl by Evelyn Clark in Lobster pot laceweight.
2. Haruni by Emily Ross in Superior,
3. Flared Lace Smoke Ring by Jackie Erickson-Schweitzer. Ok, so this one is a neckwarmer but I've had the pattern for several years.

Then there are two more patterns that I want to look at, one is Traveling Woman from feministy.com. The other is Fallen Leaf Frilled Triangular Scarflette from cottondream's etsy shop.

They are all beautiful in they're own right. Do I let the pattern choose the yarn or the yarn dictate the pattern?