Something everyone forgets is your boot size. Longer boards have wider waist widths. I'm about 5'7", 160lbs, with size 7 boots. Lots of people recommend a 155-157cm board for me at my weight but boards at those sizes may be too wide for me (most of these boards are above 25cm ww) to torsionally flex properly(unless it's a noodle).
Took me forever but I settled on a 153 Never Summer SL based on recommendations from NS and a person here. I was debating between the 153 (24.4cm ww) or 155 (25.1cm ww). Decided for my feet, the narrower board was the way to go. NS told me differences in flex between the 153 and 155 were minimal which helped make the decision even easier. Ride mainly blue groomers, trees, and in the bowls.