Still say it's Abraham.
Negan was being very observant and there was nothing random about his pick. Abraham postured up against Negan and almost looked to be at his level even while kneeling, and he took note of that. Just looking at Abraham, he knows the guy is military/trained fighter from before the zombie apocalypse, the strongest of the group (second in command perhaps) and an untameable threat. Everyone else in Rick's group is injured, sick, slumped over, exhausted from capture, crying, bewildered or plain looking defeated. The main exception is Carl and Negan did stay focused on him for a while. If he were 5-10 years older, I could see him getting the bat with the look he was giving Negan. That leaves Abraham for Negan to use to set an example.
Anyway, Abraham's death sets up Rosita forcibly moving on and seeking comfort with Eugene... and Sasha's failed suicidal revenge tactic against Negan. I guess zombie Sasha ends up killing a redshirt since Denise is already dead. This would complete Sasha's weird character development as half Andrea, half Holly. But back to Abraham, his death will be used as a catalyst for war: he was the strongest of us, we need to step up and be defiant like he was, he would have wanted us to fight yada yada. I dunno, a lot fits if Abraham dies in the premiere. Despite what some say, he's gotten tons of screen time and isn't a redshirt at this point. It is a safe kill and certainly not a Daryl or Glenn tier character and a death with the impact of a Shane or Hershel, but it still is not as insignificant as Aaron or a random Alexandrian biting it.
This all boils down to AMC meddling because they are beholden to advertisers and a large casual audience, which they are focused on not deeply offending and driving away in droves. There's unfortunate more to consider than a Game of Thrones death, so I don't see them ever killing off fan favorites like Daryl, Michonne or prematurely ending the Glenn/Maggie pairing. Really, if Game of Thrones were on AMC, they would have kept around (big GoT death spoiler)
for a longggg time (maybe forever) because of all the online chatter and mainstream attention that character got. I think AMC feels they can't "waste" main characters at this stage of the show's popularity. They are a lot less concerned with appeasing us, the comparatively small group of comic book readers and forum visitors. Basically, money talks.
A distant second for me is Aaron. There are less reasons but a similar catalyst speech can come out of it: he sought us out, trusted us, brought us into the community, gave us a new start, we owe it to him to fight, for Alexandria, yada yada. But this choice seems so damn safe to annoy even casual viewers who don't wanna see Daryl/Glenn deaths. People will be like "WHO???" especially after a 6-month break.
There was a solid fan theory that she was a Wolf and I honestly believe the writers misled us into thinking she was one with all the obvious hints being dropped. Too bad that went nowhere.