depends on why you are doing a prelim...you need a prelim for an advanced position? surgical prelim will satisfy practically every advanced specialty needing a prelim year with the exception of neurology (they require and IM prelim or TY that has 6 + months of IM). IF you are going into anesthesia or radiology , a surgical prelim might be helpful, but in general a IM prelim or TY is easier in time and work in comparison to a surgical prelim.
if you are doing a prelim GS spot in hopes of getting a cat GS spot the following year (or its back up for this), well, i guess there isn't another option, though how often this converts is not clear (AMG, probably...IMG, not so much).
if you are doing it in hopes of just getting SOMEthing...well there are more prelim GS spots that go unfilled than either IM or TY, so it probably make sense to have some IV t have on your ROL, but since they are more plentiful in SOAP (though this is a relative thing....as the years have gone by, even the number of unfilled spots are decreasing) it would be better to concentrate on getting IM or TY spots.