The best medicine school is the one that accepts you.
In terms of travelling overseas to places such as UK, USA you sit various tests and can work overseas after completion of an internship. So its not really reliant on your university, but really the hospital at which you do your internship that overseas employers will be looking at.
And lol at about deciding specialties and stuff already. As vexx said people always change. A good friend of mine who went through a Biomed pathway into grad med at ANU has changed his mind every semester on what he wants to specialise on depending on what subjects he's doing. He's 4th year atm and still has no idea on what he wants to specialise in