dvdSanta is nowhere near the best, proper AVISynth Scripting+CCE SP 2.50 9-pass VBR is probably the best software option you can get.
However I have never found dvdSanta to muck up with such problems as bad AR, out of synch, unable to encode frames, incompatible results, all of these I have had with NeroVision Express and vso's divxtodvd.
I have found even when converting NTSC XviDs to PAL DVD (when most of the others seem to stumble) all is still fine. The MPEG2 encoder is nowhere near the best. However if you are starting with a 1000kbps XviD file (what a normal downloaded XviD movie would be around) the quality of the MPEG2 encoder (encoding at around 5000kbps) will not make much difference at all. A high quality MPEG2 is really on needed when the source video is of high quality to start with (from a camcorder, or professionally mastered DVD), or if you need to encode at very low bit rates (sub 2000kbps).
As the best balance therefore of ease of use, price and quality, I can say that dvdSanta is probably the best option (however I no longer use it in favour of AVISynth+CCE).