My husband has a great office chair that has arms that flip up out of the way. I want one for myself since my sewing chair also doubles as my office chair, where I really do need arms. That's the best of both worlds!
But if your chair is going to be sewing-only, I definitely am with the group - no arms! My chair is very comfy but the arms definitely get in the way. I've even managed to pinch a quilt between the arm and the table and have a seam go sideways because of the tug...more than once! Argh!