同意一楼
不过三者之间有些许不同.
I didn't speak to anyone.
语气较重,汉语可以理解为我跟谁也没说话.
I speak to no one.
设置一个场景有助于理解这个哨位差别：
Whom are you speaking to?
I speak to no one.I'm talking to myself.There is nobody here.
I speak to nobody.
There are so many people,whom did you speak to?
I spoke to nobody.
平时用时三者意思相当.