Depends on what kinda display you'll be viewing the output on.
If it's a native 16:9 display(no letterbox), you can render to widescreen NTSC(960x480, PAR=1.2121) If the native display is 4:3 and you want letterboxed 16:9, use DV (720x480, PAR=.9091) If you don't know or if you want the most flexibility in output format, use the DV (not widescreen) template.
Sometimes, like if you use the HuffyUV codec as an intermediate codec, the codec will reset the output PAR to 1.0. I always load the redered video into V5 Media Pool to check the header PAR setting. It may need to be reset.