I see it this way.
Time in the hospital vs. Time outside of the hospital.
What is your priority for internship or life in general. Is your "non-medicine" interest #1? or is "medicine" your #1? Do you want more time off to study for step 3? Are you married? Would your sig-other want to move twice, find a new job... but get to see you more often at home? TY usually will allows for more flexibility in your life.
Variety vs. Repetition
Do you want more variety in your internship year? Are you the type that can learn "necessary" medicine in 3 months or 6 months? Do you want to delve deeper into Medical Zebras or do want more variety in different fields? TY usually offer more electives. Heck, You can even do OB/GYN and PEDS too! Wonder why it is not required for Anes-PGY-1 since we will be taking care of OB/PEDS patients. (Kudos to Maine Program for the awesome PGY-1 design) Personally I think variety will better prepare you for anesthesiology. A blend of surgery, medicine, icu, ER, OB, pain, geriatric, pulm, card, renal, GI, peds....boy, we take care of a WIDE VARIETY of patients!!!! 🙂 (you can throw in psych for pain clinic).
Costs
Moving is a big hassle and costly. New apartments, addy, insurance, license plates, etc.
Learning the Hospital System once vs. twice.
Are you very good with computers and IT system? Can you pick up EMR quickly??? Learning a whole new system is a big hassle. Staying in the same system, you get to know your surgeons, nurses, meds, peds, ob colleagues... If you want to get a head start on learning the hospital system, I would suggest in staying in the same location.
In the end, you can't go wrong either way. If you apply yourself, transitional year will be just as good. Being a "real" doctor is so subjective these days. I say if you sincerely care for your patients, no matter where you did your internship, you're a real doc. But what do I know, I'm just an MS4 like you.