"To me"or"For me"

[DreamFounder]

Hello guys.
Which of the following sentences are/is correct or possible?
1. For me, it's too difficult.
2. To me, it's too difficult.
3. As for me, it's too difficult.
4. As to me, it's too difficult.
5. As for me, I don't like it anymore.
6. As to me, I don't like it anymore.

[Casiopea]

These are not possible:

4. *As to me, it's too difficult.
6. *As to me, I don't like it anymore.

I speak North American English.