genoa
if you know that you're only going to have light air.........I would go with the biggest you can afford (150%-155%) knowing that you can furl up about 25% of it and still have it work well. If you are always in air that is overpowering you , go with a smaller (135%) genoa (which can roll up to around 100%. The best choice is having 2 headsails. I a heavy air #3 and a light air #1