I feel like the reason they're even doing a cliffhanger is so they can focus test the different scenarios during pre-production, and potentially change their mind before they begin shooting season 7.
I do agree that Daryl should've likely been the prime candidate for the Lucille treatment, for a number of reasons. Daryl has been a security blanket of sorts for the group - tough & able whenever they need someone to be, as well a problem solver when the situation arises. Negan's introduction was meant to shatter the sense of security that the concept of Alexandria had built for the comic audience. Doing that with Daryl would've been poetic, as hes been one of the group's strongest soldiers up to this point.
It's odd how the show gets so indecisive about taking elements from the comic when it wants. Particularly because the things it did give us have, in my opinion, been improvements overall to the comic. I like that we didn't have to deal with some BS serial killer in the jail ( or rather, that they reinterpreted that to be Carol & the flu). Or that Lori died during child-birth and Carl had to put down zombie-Lori. Or that Shane made it all the way to Hershel's farm. Or Morgan's show backstory and how he was reintroduced to the group. Not to mention him becoming unhinged in 'clear' was a better use of the character than the comic.
And even when they do make drastic mistakes in the liberties they do take from the comics (all of Andrea's character arc, Tyreese's show interpretation) I do feel that they do eventually correct some of those missteps. Speaking of which, what is up with Tyreese & Morgan essentially being very similar characters? Tyreese basically adopted this quiet workhorse persona on the show which was unlike his comic counter-part. Then, Tyreese adopts Morgan's current mantra, a full-season before Morgan is reintroduced into the group.