Don't get mad, get even!

 

Definitely, I think "we need to talk" is the best because you are emotionally preparing the other person to talk about a break up or possible break up. The worst without a doubt is the line "I don't love you anymore" because must be very cruel hear that’s words when you are completely in love of the person that have said it.
"You’re a fantastic person, but you're too good for me".  Yes, I have said, but when I said it, was real. No was a pretext.
In conclusion, I think none line would be good when it comes to a break up. Fortunately, I haven't had to go through any yet.