Of the 3 promotional singles (NLTM, CTD, ET), ET has the highest peak on the Hot 100. I think she would be best releasing that as the next single. People have already stated that "Peacock" will have to be edited down on radio, and also she could never perform the song on TV without the same edits, and that would just be tragic to hear.
I think ET is going to get released. She's gonna get talked out of releasing Peacock, for better or worse.
Last Friday Night is too generic and Peacock, at this point, is too predictable.
But then again, Rihanna and Katy Perry fans do love their generic pop.
No doubt that LFN is another generic pop song produced by Dr luke, but its guaranteed a smash hit on the charts. People love catchy and generic pop songs nowadays. which is why katy sell lots of singles. look at kesha for e.g