I just went by my own likes and dislikes. I generally dislike internal medicine in practice (not in theory though). The old people nursing home admits all night, the rounding, the dumps from ortho and neuro who hate to admit their own pts...I could go on and on. So I never really considered prelim medicine.
Transitional let me take 2 months of gen. int. med, peds, 2 months surg, Pulm, cardio, EM, 2 ICU months, ENT, and anesthesia. Note the 7 call free months as well... I've had a pretty good intern year so far!
I toyed with the idea of prelim surgery as well. Less BS than medicine, but more than TY. There have been times I wished I had gone this route. Where I'm at, as in intern you actually get to operate. Even on my 2 months I was doing appys, breast biopsies, etc. But it is a lot of time to learn a skill that I would never be doing again.
There are people that say medicine will prepare you the best. They're probably right, but if I was miserable for a year then that's not going to help me in the long run. And the medicine prelims I happened to be exposed to were all sooooo unbelieveably bad that they pretty much made up my mind for me.
