If that's the case I would rank the Prelim IM spots higher (even if the IM prelim year may be more work than a TY year).
Very few IM programs that have a PGY-2 opening will accept someone to transfer in as a PGY-2 who did a TY as their PGY-1 year (which includes rotations in multiple specialty areas in IM as well as Surgical specialties), while most will accept someone who did a PGY-1 prelim year. PGY-2 IM positions are not through the Match and usually open when a PGY-1 categorical leaves the program for some reason or if a program is expanding, so your options will be more limited. Also, if you are doing IM residency to pursue a competitive fellowship (Eg cardiology, GI, heme/onc, pulm/crit), coming from a "no name" IM program will severely limit your chances of matching.
The main difference between a PGY-1 categorical year vs a Prelim year at most programs is that the prelim year does not have outpatient (ambulatory) continuity clinic, so most people who transition from prelim to categorical only end up doing 2 years of