Depende do contexto. No contexto abaixo, podem ser usados como sinônimos.
To me, she's the best actress in Brazil.
For me, she's the best actress in Brazil.
Exemplo do 'The New York Times':
''For me, it's a dream to go to training and then see a game of football, basketball, whatever game. For me, New York is the best city in the world.''
Exemplo da revista americana 'Forbes':
''To me, it is confusing why spending has still increased under the Obama administration even after the tremendous increase in the federal...''