It depends on the city. In LA, a transitional year is not easy to come by. Actually, it’s more difficult to get a (medical) preliminary or transitional year than it is to match in a categorical FP or IM program. The reason is: there’s limited number of slots for prelim/transitional…and many specialties require them.
I’d try to apply for a categorical spot…and use a medical prelim as back up. There are also surgical prelim spots (which are a bit less competitive because there are more of ’em). Easier specialties are those with lots of postitions…such as FP, IM, and maybe even psyche. Surgery hasn’t been as tough lately, so perhaps you’d even have a good chance of matching in a surgery program.
I can only speak for LA area…things vary depending on where you wanna train (of course).