I'm hoping this is one that is EASY for you to check off.
This time of year especially, but I would argue ALL YEAR ROUND we need at least one neutral pullover (and/or cardigan). I have found over the years that a shade of gray that works for you is probably the most neutral, but you could also choose oatmeal or tan.
I think a v-neck is the most versatile too but you may prefer a crew neck and that's fine too…(and very on trend right now, especially with a white crew t-shirt under it). Below are 2 favorite picks that come in several classic neutrals: