im almost at that point too. i have diffuse thinning, temple recession, and after looking at recent pictures im developing a bald spot. i've spent a year trying treatments and worrying about hairloss constantly. it has really affected my life and i've isolated myself because of it.
i shaved my head about 6 months ago on #3. i didnt really like it because with my diffuse thinning it showed a lot of scalp. so i've kept my hair really long since then. but now even with long hair its really hard to hide. so im thinking about shaving it again.
i would probably start with #2 and then see how it looks. you can always go shorter if you want to.