I have a lot of problems choosing my quilting design. My brain just doesn't see what others do in terms of what others see.
Usually when I stitch in the ditch, I'm actually stitching in the ditch, for this though I would be over 1/4-1/2" away from the branch part and using a background color thread, just stitch those diagonal channels first, then see what else it needs from there, whether to go both horizontal and vertical, or maybe just one.
An all over edge to edge swirly meander design would look nice too. Can be leafy-inspired maybe without being too noticeable, maybe a vine with an occasional leaf sprouting off it would be ok??