It's really just a matter of what you're comfortable with. I started out with NURBS mostly for the fact because I had a difficult time getting objects smoothed right in poly, and for the fact that NURBS already has UVs laid out. Unfortunately, NURBS also are a lot more finicky to work with which is why I seldom use them anymore except for certain things. They aren't as straight forward as polygon modeling, which like others have said, is like working with clay...or if you're modeling poly by poly, like a spider weaving a web.
Personally, I mostly opt for box modeling using poly proxy (where I have the smoothed proxy side by side with the raw model I'm tweaking) or building a model poly by poly. The idea of this is that you create a polygon then keep extruding edges/merging vertices into the shape you want. Both are pretty quick as far as getting basic shapes. I've never really sat at length using sub-d...always gets a little confusing for me and using poly proxy when box modelling is essentially the same result.
"Terminat Bora Diem, Terminal Auctor opus."