If you are going to use a DVD authoring tool that accepts MPEG2 files then your should render to MPEG2 at DVD quality. If your DVD authoring tool does not accept pre-rendered MPEG2 files then you should render to AVI at DV quality. MPEG1 is really meant for lower quality Video CD’s not DVD’s. (but can be used on DVD to get 4 hours of low quality video if needed)
I suggest rendering to MPEG2 to save rendering time if you can.