I weight a little more than you and I'm a woman, which means I have a pretty, um, "noticeable" butt and belly. All my saddles are 16's or 17's.
I would say it depends a lot on the style of the saddle. I've been riding in A-forks and wades with high cantles. A 17 fits me best in that style because the cantle comes up high and cradles your butt. But I have also ridden in 17's that are more flat seated, roper type saddles and they are huge in a 17, way too big for me! So my gut feeling, since you're a guy, is that a 16 would work for you just fine. Most guys have less butt than a woman of similar weight.
But the best thing to do would be to sit in your prospective saddles (or ones of the same style if, say, you are ordering online) so you have an idea of how much room you like. Because some of that is personal preference. I used to like big, roomy saddles until I started riding a 2 yr old. Now I kind of like my saddles to fit tighter.
Anyway, I guess the point I am trying to make is, it depends on the style of saddle. Some 17's fit more like a 16, and some are downright huge. And I don't think you should rule out 16's until you sit in a few either. They can also run large and small.