Size 6, definitely. If a pattern doesn’t specify I always default to my trusty sixes. I don’t like larger needles because they hurt my hands, but smaller is ok. I’m weird like that.
I don’t think that’s weird at all, stitchywitch. When I knit with 15’s it was very uncomfortable and I felt like I had less control over them than I do smaller needles.
It’s funny, my first thought was a US 4, but that’s just since I’ve been working on a sweater for like months and don’t remember what it’s like to use anything else! But yeah, something a little larger like an 8 would be more flexible.